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Hesitancy to receive the COVID-19 vaccine among healthcare workers (HCWs) in low-resource settings, such as the Democratic Republic of the Congo (DRC), is a major global health challenge. This study identifies changes in willingness to receive vaccination among 588 HCWs in the DRC and reported influences on COVID-19 vaccination intentions. Up to 25 repeated measures were collected from participants between August 2020 to August 2021. Among the overall cohort, between August 2020 and mid-March 2021, the proportion of HCWs in each period of data collection reporting COVID-19 vaccine hesitancy ranged from 8.6% (95% CI: 5.97, 11.24) to 24.3% (95% CI: 20.12, 28.55). By early April 2021, the proportion reporting hesitancy more than doubled (52.0%; 95% CI: 46.22, 57.83). While hesitancy in the cohort began to decline by late-June 2021, 22.6% (95% CI: 18.05, 27.18) respondents indicated hesitancy in late-August 2021 which remains greater than the proportion of hesitancy at any time prior to early-March 2021. Patterns in reported influences on COVID-19 vaccination were varied with the proportion reporting some influences (e.g., no serious side effects, country of vaccine production) remaining stable throughout the year and other factors (e.g., recommendation of Ministry of Health, ease of vaccination) falling in popularity among respondents. Agreement that the national vaccination schedule should be followed apart from the COVID-19 vaccine remained high among respondents throughout the study period. This study shows that, among a cohort of HCWs in the DRC who have likely been influenced by regional, national, and global factors, COVID-19 vaccine hesitancy has fluctuated during the pandemic and should not be treated as a static factor. Additional research to determine which factors most influence HCWs' willingness to receive the COVID-19 vaccine offers opportunities to reduce vaccine hesitancy among this important population through tailored public health messaging.

• A seroprevalence study and survey in healthcare workers (HCWs) were conducted in a tertiary care hospital from 2017 to 2022. • Measles seropositivity declined gradually from >90 % in the HCWs born in the 1960s to <80 % in those born in the 1990s. • The seropositivity for VZV was stable at >90 %. • The self-reported history was not sufficiently reliable for screening HCWs. To examine the seroprevalence of measles and varicella zoster virus (VZV) among healthcare workers (HCW) and evaluate the concordance between self-reported history of previous disease or vaccination and seropositivity. A seroprevalence study and survey. A university-affiliated tertiary care hospital. All HCWs working in high-risk services in 2017 underwent serologic tests and survey; all new HCWs employed in the subsequent years, serologic tests only. A serologic study was conducted using chemiluminescence immunoassay (2017) or enzyme immunoassays (2018 and later). HCWs who underwent serological testing in 2017 completed a self-administered questionnaire on their history of infection and vaccination. A total of 10,278 and 9607 HCWs underwent serologic tests for measles and VZV IgG, respectively, from 2017 to 2022. The overall seropositivity rates for measles and VZV were 78.1 % and 92.8 %, respectively. Measles seropositivity declined gradually from >90 % in the HCWs born in the 1960s to <80 % in those born in the 1990s. There was a significant difference in measles seropositivity between the birth cohorts (BCs) 1967–1984 and 1985–1999 (P < 0.001; odds ratio, 1.16; 95 % confidence interval, 1.14–1.18). The seropositivity for VZV was stable, at >90 % in all BCs. The self-reported vaccination history was not independently associated with seropositivity, and the negative predictive value of the survey was very low (9.6 % and 13.1 %, respectively). Measles seropositivity showed a substantial decline among HCWs born in 1985 or later, while varicella seropositivity remained high. The self-reported vaccination history was not sufficiently reliable for screening HCWs. [ABSTRACT FROM AUTHOR]

Health care workers (HCW) have a higher exposure to SARS-CoV-2 virus than other professionals and to protect both HCW and patients, HCW have been prioritized for vaccination against SARS-CoV-2 in many countries. Estimating the COVID-19 vaccine effectiveness among HCW is important to provide recommendations to protect risk groups. We estimated vaccine effectiveness against SARS-CoV-2 infections using Cox proportional hazard models among HCW with comparisons in the general population, from 1 August 2021 to 28 January 2022. Vaccine status is specified as a time-varying covariate and all models incorporated explicit time and were adjusted for age, sex, comorbidities, county of residence, country of birth, and living conditions. Data from the adult Norwegian population (aged 18–67 years) and HCW workplace data (as registered 1 January 2021) were collated from the National Preparedness Register for COVID-19 (Beredt C19). Vaccine effectiveness was higher for Delta than for the Omicron variant in HCW (71 % compared to 19 %) as well as in non-HCW (69 % compared to −32 %). For the Omicron variant a 3rd dose provides significantly better protection against infection than 2 doses in both HCW (33 %) and non-HCW (10 %). Further, HCW seem to have better vaccine effectiveness than non-HCW for the Omicron, but not for the Delta variant. Vaccine effectiveness were comparable between HCW and non-HCW for the delta variant, but significantly higher in HCW than non-HCW for the omicron variant. Both HCW and non-HCW got increased protection from a third dose. [ABSTRACT FROM AUTHOR]

• Most HCPs are COVID-19 vaccinated and recommend vaccination to patients, although proportions vary by HCP type. • Unvaccinated HCP harbor many similar concerns to the public. • HCP need sufficient resources to confidently discuss vaccines with patients. Increasing vaccine coverage remains the best way to control the COVID-19 pandemic. Healthcare personnel (HCP) have long been the most credible and frequently used source of vaccine information for the public, and an HCP recommendation is a strong predictor of vaccination. A survey of HCP was conducted in September 2021 via a double opt-in network panel. Responses to survey items were summarized and stratified by HCP type and adjusted logistic regression models were fitted. >94% of the 1074 HCP surveyed reported receiving at least one dose of COVID-19 vaccine or intending to soon, with vaccinating most common among pediatricians (98%), followed by family medicine doctors (96%), pharmacists (94%), and nurses/nurse practitioners/physician assistants (88%). HCP with high trust in the Centers for Disease Control and Prevention had 26 times the odds of vaccinating of HCP with low trust (95%CI: 9, 74). Nearly half of unvaccinated HCP (47%) were concerned about side effects, and one third of unvaccinated HCP (33%) were concerned the vaccine was developed too quickly. About three quarters of HCP reported strongly recommending the Pfizer-BioNTech (75%) and Moderna (70%) vaccines to their patients, compared to about one quarter (24%) strongly recommending Johnson & Johnson. Although most HCP are vaccinated against COVID-19 and strongly recommend vaccination to their patients, some harbor similar concerns to the public. Additional resources – regularly updated to explain the progressing scientific landscape and address ever evolving public concerns – are needed to further improve vaccine coverage among HCP and aid them in supporting the decision-making of their patients. [ABSTRACT FROM AUTHOR]

Vaccination of healthcare workers against influenza is a crucial strategy to reduce transmission amongst vulnerable populations, facilitate patient uptake of vaccination, and bolster pandemic preparedness. Globally, vaccination coverage of health workers varied from 10 % to 88 %. Understanding health workers' knowledge and acceptance of the influenza vaccine, particularly among physicians, is crucial for the fine-tuning and continued success of influenza vaccination campaigns. We conducted a cross-sectional survey of 472 health workers in Abidjan, Côte d'Ivoire, to inform subsequent subnational and national introductions of influenza vaccine and subsequent campaigns targeting health workers in 2019 (14 302), 2020 (14 872), and 2021 (24 473). Using a purposive sample of university hospitals, general hospitals, rural, and urban health facilities, we interviewed a convenience sample of health workers aged 18 years and older. Physicians had the lowest intention to receive the influenza vaccine (58 %), while nurses (78 %) and midwives (76 %) were the most willing. Across all occupations, intention to receive vaccination increased if the vaccine was offered for free or if recommended by the Ministry of Health. 76 % of respondents believed that the influenza vaccine could prevent illness in health workers. Communication strategies, including about the benefits of influenza vaccination, could raise awareness and acceptance among health workers prior to vaccination campaigns. Influenza vaccination coverage rates between 2019 and 2021 were on par with rates of intention to receive vaccination in the 2018 survey; in 2019, 2020, and 2021, coverage among physicians was 73 %, 73 %, and 52 % and coverage among nurses and midwives was 86 %, 86 %, and 74 % respectively. Improving health workers' knowledge and acceptance of the influenza vaccine, particularly among physicians, is crucial for the continued success of influenza vaccination campaigns. [ABSTRACT FROM AUTHOR]

• Migrant family needs are not well considered in the Australian National Immunisation Program. • System improvements are required to support service delivery to migrants. • General practitioners had limited time, skills, and motivation for catch-ups. • Resources and training are needed to support catch-up scheduling and reporting. • Funding provider time to calculate the schedule could overcome most limitations. Current models of immunisation service delivery in Australia are not meeting the needs of migrant children, who experience a higher burden of vaccine preventable disease and lower immunisation rates compared to non-migrant children. Understanding the experiences of immunisation providers is critical for designing effective and tailored interventions to improve this service. This study aimed to identify the facilitators and barriers to providers delivering a comprehensive catch-up immunisation service to migrant children in Melbourne, Australia. Semi-structured interviews with council and general practice immunisation providers were conducted. Recorded interviews were transcribed and coded inductively using thematic analysis. Identified themes were then deductively categorised according to the Capability, Opportunity and Motivation of Behaviour (COM-B) model. Twenty-four providers (five practice nurses, six general practitioners, six council nurses and seven council administration officers) were interviewed between March and June 2021. Fourteen themes were identified that contributed to the delivery of an effective catch-up immunisation service. Capability themes included training, experience and skills to perform the service and communicate with families. Opportunity themes incorporated time, workplace norms, traits of migrant families, costs, systems and resources. Themes related to motivation were provider responsibility, beliefs about migrant health, and immunisation prioritisation. Key barriers for providers to deliver a comprehensive catch-up immunisation service were related to opportunity. Developing an online tool to support catch-up schedule development and reporting, and funding provider time to calculate the schedule are primary actions that could overcome opportunity barriers. Capability and motivation barriers for general practitioners included limited time, skills, and motivation compared to nurses. These barriers may be overcome with improvements to training that focus on upskilling nurses to deliver the catch-up service. Service delivery challenges are multifactorial, requiring a range of strategies to optimise this service and increase immunisation coverage in migrant children. [ABSTRACT FROM AUTHOR]

Community engagement is vital to the development of people-centered, successful vaccination programs. The diverse Vaccination Acceptance Research Network (VARN) community brings together interdisciplinary professionals from across the immunization ecosystem who play a crucial role in vaccination acceptance, demand, and delivery. Over the course of the VARN2023 conference, researchers and practitioners alike shared ideas and experiences focused on strategies and approaches to building trust between communities and health systems to increase equity in vaccination. Health professionals and community members must have equal value in the design and delivery of community-centered immunization services, while key vaccination decision-makers must also consider community experiences, concerns, and expertise in program design and policymaking. Therefore, strategies for community engagement and cultivating trust with communities are crucial for the success of any immunization program. Furthermore, health workers need additional skills, support, and resources to effectively communicate complex information about immunization, including effective strategies for countering misinformation. This article summarizes three skills-building sessions offered at the VARN2023 conference, focused on human-centered design, motivational interviewing, and engaging with journalists to leverage the voices of communities. These sessions offered practical, evidence-based tools for use across geographic and social settings that can be used by practitioners, researchers, and other stakeholders to increase vaccination demand and uptake in their communities., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [NPR, KLH, TS, and AG are Sabin employees. TU is a consultant for the Sabin Vaccine Institute (Sabin). GL, CK, DRP, and EL are UNICEF employees. LM, ABC, PK, JS, NR, and MK were VARN2023 delegates who spoke on related topics and/or co-organized and/or facilitated the VARN2023 side events on human-centered design, motivational interviewing, and journalist engagement.]., (Copyright © 2024. Published by Elsevier Ltd.)

Background: Nigeria has the largest number of children infected with hepatitis B virus (HBV) globally and has not yet achieved maternal and neonatal tetanus elimination. In Nigeria, maternal tetanus diphtheria (Td) vaccination is part of antenatal care and hepatitis B birth dose (HepB-BD) vaccination for newborns has been offered since 2004. We implemented interventions targeting healthcare workers (HCWs), community volunteers, and pregnant women attending antenatal care with the goal of improving timely (within 24 hours) HepB-BD vaccination among newborns and Td vaccination coverage among pregnant women., Methods: We selected 80 public health facilities in Adamawa and Enugu states, with half intervention facilities and half control. Interventions included HCW and community volunteer trainings, engagement of pregnant women, and supportive supervision at facilities. Timely HepB-BD coverage and at least two doses of Td (Td2+) coverage were assessed at baseline before project implementation (January-June 2021) and at endline, one year after implementation (January-June 2022). We held focus group discussions at intervention facilities to discuss intervention strengths, challenges, and improvement opportunities., Results: Compared to baseline, endline median vaccination coverage increased for timely HepB-BD from 2.6% to 61.8% and for Td2+ from 20.4% to 26.9% in intervention facilities (p < 0.05). In comparison, at endline in control facilities median vaccination coverage for timely HepB-BD was 7.9% (p < 0.0001) and Td2+ coverage was 22.2% (p = 0.14). Focus group discussions revealed that HCWs felt empowered to administer vaccination due to increased knowledge on hepatitis B and tetanus, pregnant women had increased knowledge that led to improved health seeking behaviors including Td vaccination, and transportation support was needed to reach those in far communities., Conclusion: Targeted interventions significantly increased timely HepB-BD and Td vaccination rates in intervention facilities. Continued support of these successful interventions could help Nigeria reach hepatitis B and maternal and neonatal tetanus elimination goals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

The level of neutralizing antibodies required to confer protection against COVID-19 breakthrough infections (BIs) is unclear, and the ability to know the immune status of individuals against the rapidly changing endemic variants is limited. We assessed longitudinal serum anti-RBD antibody levels and neutralizing activities (NTs) against Omicron BA.5 and XBB.1.5 in healthcare workers following the fourth monovalent and fifth bivalent BA.4-5 vaccines. The occurrence of BIs was also followed, and pre-infection antibody levels were compared between patients who developed BI and those who did not. In addition, we collected whole blood samples on the same day as the sera and stored them on filter papers (nos. 545, 590, and 424) for up to two months, then measured their NTs using dried blood spots (DBS) eluates, and compared them with the NTs in paired sera. Pre-infection levels of NTs were lower in patients who developed BI than those who did not, but the anti-RBD antibody levels were not different between them. The NTs below 50 % using 200-fold diluted sera might be one of the indicators of high risk for COVID-19 BI. However, the NTs against XBB.1.5 at 6 months after the fifth dose of bivalent BA.4-5 vaccine were lower than this threshold in almost half of infection-naïve participants. NTs measured using DBS eluates were strongly correlated with those measured using paired sera, but the time and temperature stability varied with the type of filter paper; no. 545 filter paper was found to most suitable for NT evaluation., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: ‘ADVANTEC provide filter papers for neutralizing antibody assays. We have no conflicts of interest to declare.’., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

ObjectiveHealthcare providers (HCPs) are advised to give all parents a strong recommendation for HPV vaccination. However, it is possible that strong recommendations could be less effective at promoting vaccination among African Americans who on average have greater mistrust in the healthcare system. This study examines the associations of parental trust in HCPs and strength of HCP vaccination recommendation on HPV vaccine acceptance among African American parents.MethodsParticipants were recruited from an urban, academic medical center between July 2012 and July 2014. We surveyed 400 African American parents of children ages 10-12years who were offered HPV vaccine by their HCPs to assess sociodemographic factors, vaccine beliefs, trust in HCPs, and the HPV vaccine recommendation received. Medical records were reviewed to determine vaccination receipt.ResultsIn multivariable analysis, children whose parents were "very strongly" recommended the HPV vaccine had over four times higher odds of vaccine receipt compared with those whose parents were "not very strongly" recommended the vaccine. Having a parent with "a lot of" versus "none" or only "some" trust in HCPs was associated with over twice the odds of receiving HPV vaccine. Very strong HCP recommendations were associated with higher odds of vaccination among all subgroups, including those with more negative baseline attitudes toward HPV vaccine and those with lower levels of trust. Adding the variables strength of HCP recommendation and parental trust in HCPs to a multivariable model already adjusted for sociodemographic factors and parental vaccine beliefs improved the pseudo R2 from 0.52 to 0.55.ConclusionsAmong participants, receiving a strong vaccine recommendation and having a higher level of trust in HCPs were associated with higher odds of HPV vaccination, but did not add much to the predictive value of a model that already adjusted for baseline personal beliefs and sociodemographic factors.

Healthcare workers (HCWs) are recommended to receive at least three spike-antigen exposures to generate basic immunity and to mediate herd protection of vulnerable patients. So far, less attention has been put on the cellular immune response induced by homologous (three BTN162b2mRNA doses) or heterologous (mRNA-1273 as third dose building on two BTN162bmRNA doses) and the immunological impact of breakthrough infections (BTIs). Therefore, in 356 vaccinated HCWs with or without BTIs the Anti-SARS-CoV-2-Spike-IgG concentrations and avidities and B- and T-cell-reactivity against SARS-CoV-2-Spike-S1- and Nucleocapsid-antigens were assessed with Interferon-gamma-ELISpot and by flow-cytometry. HCWs who had hybrid immunity due to BTIs exhibited strong T-cell-reactivity against the Spike-S1-antigen. A lasso regression model revealed a significant reduction in T-cell immune responses among smokers (p < 0.0001), with less significant impact observed for age, sex, heterologous vaccination, body-mass-index, Anti-Nucleocapsid T-cell reactivity, days since last COVID-19-immunization, and Anti-SARS-CoV-2-Spike-IgG. Although subgroup analysis revealed higher Anti-SARS-CoV-2-Spike-IgG after heterologous vaccination, similar cellular reactivity and percentages of Spike-reactive T- and B-cells were found between homologous and heterologous vaccination. Anti-SARS-CoV-2-Spike-IgG concentrations and avidity significantly correlated with activated T-cells. CD4 + and CD8 + responses correlated with each other. A strong long-term cellular immune response should be considered as baseline for recommendations of booster doses in HCWs with prioritization of smokers. HCWs presented significant T-cellular reactivity towards Spike-S1-antigen with particularly strong responses in hybrid immunized HCWs who had BTIs. HCWs without BTI presented similar percentages of Spike-specific B- and T-cells between homologous or heterologous vaccination indicating similar immunogenicity for both mRNA vaccines, BNT162b2mRNA and mRNA-1273., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Martina Prelog received honoraria for presentations at scientific meetings from Abbvie, BioNTech, Chugai-Roche, Doctorflix, GSK, Esanum, Janssen, Novartis, Moderna, MSD, Pfizer, Sanofi and SOBI, received honoraria for advisory boards from Abbvie, BioNTech, GSK, Janssen, Moderna, Novartis, and Pfizer , received travel scholarships from Chugai-Roche, GSK, Novartis and Pfizer, received financial support for conduction of investigator-initiated research from Baxter, Chugai-Roche, Galapagos,  GSK, Moderna, Novartis, MSD, Pfizer and SOBI; Martina Prelog declares to have no conflict of interest regarding the manuscript.  Manuel Krone receives honoraria from GSK and Pfizer outside the submitted work. All other authors declare no potential conflicts of interest. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper]., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objective: This study aimed to evaluate the effectiveness of SARS-CoV-2 mRNA vaccines in preventing infection and hospitalization among healthcare workers (HCWs) in the Valencian Community (Spain), considering vaccination timing, dose number, and predominant variant., Methods: A test-negative case-control design estimated vaccine effectiveness against symptomatic disease and hospitalization due to SARS-CoV-2. HCWs who underwent PCR or antigen testing for SARS-CoV-2 from January 2021 to March 2022 were included. Cases had a positive diagnostic test, while controls had negative tests. Adjusted vaccine effectiveness (aVE) was calculated using the formula: aVE = (1 - Odds ratio) × 100., Results: During the Delta variant's predominance, aVE against infection within 12-120 days post-second dose was 64.8 % (BNT162b2) and 59.4 % (mRNA-1273), declining to 21.2 % and 42.2 %, respectively, after 120 days. For the Omicron variant, aVE within 12-120 days post-second dose was 61.1 % (BNT162b2) and 85.1 % (mRNA-1273), decreasing to 36.7 % and 24.9 %, respectively, after 120 days. After a booster dose of mRNA-1273, aVE was 64.0 % (BNT162b2 recipients) and 65.9 % (initial mRNA-1273 recipients). Regardless of variant, aVE for hospitalization prevention after 2 doses was 87.0 % (BNT162b2) and 89.0 % (mRNA-1273)., Conclusion: The administration of two doses of Moderna-mRNA-1273 against SARS-CoV-2 in HCWs proved to be highly effective in preventing infections and hospitalizations in the first 120 days after the second dose during the predominance of the Omicron variant. The decline in VE after 120 days since the administration of the second dose was significantly restored by the booster dose administration. This increase in VE was greater for the Pfizer vaccine. COVID-19 hospitalization prevention remained stable with both mRNA vaccines throughout the study period., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Standing orders may improve HPV vaccination rates, but clinical staff's readiness to use them has not been well-explored. We sought to explore benefits and challenges to using HPV vaccine standing orders for adolescents ages 9 to 12, understand clinical staff roles in communication about HPV vaccine, and how standing orders can reduce barriers contributing to vaccine disparities among racial and ethnic marginalized groups., Methods: Participants were a sample of 16 U.S. nurses, medical assistants, and healthcare providers working in primary care, recruited from June to September 2022. Trained staff conducted virtual, semi-structured qualitative interviews. We analyzed the resulting data using reflexive thematic analysis., Results: Themes reflected benefits and challenges to using HPV vaccine standing orders and strategies to address clinic barriers to improve vaccine access and HPV vaccine communication. Benefits included faster and efficient clinic flow; fewer missed vaccine opportunities and promotion of early vaccination; and normalization of HPV vaccination as routine care. Challenges included possible exacerbation of existing HPV vaccine communication and recommendation barriers; and how the complexity of the vaccine administration schedule lessens nurses' and medical assistants' confidence to use standing orders. Strategies to address vaccine access barriers included using nurse-only visits to empower nurse autonomy and catch up on HPV vaccination; engaging clinical staff to follow up with overdue children; and educating parents on HPV vaccine before their child is vaccine eligible., Conclusion: Using HPV vaccine standing orders can promote autonomy for nurses and medical assistants and address vaccine access barriers. Clinical staff engagement and clinic support to mitigate existing vaccine communication barriers are needed to empower staff to use of HPV vaccine standing orders., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Dr. Brewer has served as a paid consultant for Merck, the Centers for Disease Prevention and Control, and the World Health Organization. Mr. Kahn has served as a paid consultant for the World Health Organization. All other authors declared no potential conflicts of interest]., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Introduction: The long-term impact of initial immunogenicity induced by different primary COVID-19 vaccine series remains unclear., Methods: A prospective cohort study was conducted at 10 tertiary hospitals in Korea from March 2021 to September 2022. Immunogenicity assessments included anti-spike protein antibody (Sab), SARS-CoV-2-specific interferon-gamma releasing assay (IGRA), and multiplex cytokine assays for spike protein-stimulated plasma. Spike proteins derived from wild-type SARS-CoV-2 and alpha variant (Spike 1 ) and beta and gamma variant (Spike 2 ) were utilized., Results: A total of 235 healthcare workers who had received a two-dose primary vaccine series of either ChAdOx1 or BNT162b2, followed by a third booster dose of BNT162b2 (166 in the ChAdOx1/ChAdOx1/BNT162b2 (CCB) group and 69 in the BNT162b2/BNT162b2/BNT162b2 (BBB) group, based on the vaccine series) were included. Following the primary vaccine series, the BBB group exhibited significantly higher increases in Sab levels, IGRA responses, and multiple cytokines (CCL2/MCP-1, CCL3/MIP-1α, CCL4/MIP-1β, interleukin (IL)-1ra, IFN-γ, IL-2, IL-4, and IL-10) compared to the CCB group (all P < 0.05). One month after the third BNT162b2 booster, the CCB group showed Sab levels comparable to those of the BBB group, and both groups exhibited lower levels after six months without breakthrough infections (BIs). However, among those who experienced BA.1/2 BIs after the third booster, Sab levels increased significantly more in the BBB group than in the CCB group (P < 0.001). IGRA responses to both Spike 1 and Spike 2 proteins were significantly stronger in the BBB group than the CCB group after the third booster, while only the Spike 2 response were higher after BIs (P = 0.007). The BBB group exhibited stronger enhancement of T-cell cytokines (IL-2, IL-4, and IL-17A) after BIs than in the CCB group (P < 0.05)., Conclusion: Differences in immunogenicity induced by the two primary vaccine series persisted, modulated by subsequent booster vaccinations and BIs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Healthcare personnel vaccinations are important to prevent vaccine-preventable diseases in hospitals. We evaluated the seroprevalence, vaccination rates, and barriers to vaccination among newly employed nurses and doctors. A cross-sectional study was conducted at a university hospital in the Republic of Korea from 2017 to 2020. The immune status for hepatitis B virus (HBV), varicella zoster virus (VZV), and hepatitis A virus (HAV) was tested. HBV, VZV, measles, mumps, and rubella (MMR) vaccinations were mandatory. HAV and tetanus-diphtheria-pertussis (Tdap) vaccinations were also recommended by specialists. A web-based survey on factors affecting vaccination completion was conducted. For the 668 participants, the mean age was 26 ± 2 (±SD) years. Seroprevalence was 86% for HBV, 93% for VZV, and 59% for HAV. Vaccine completion rates were 40% for HBV, 70% for VZV, 65% for MMR, 42% for HAV, and 70% for Tdap. Overall compliance for mandatory vaccines was 54%. A total of 402 subjects who had worked for over one year were surveyed, with a 22% response rate. More than 50% of respondents gave the following reasons for not receiving recommend vaccines: 1) they were busy (77%), 2) vaccination process was complicated (68%), and 3) they simply forgot about vaccination (55%). Healthcare personnel agreed to be frequently informed of immunization requirements and for monitoring of vaccination rates. Vaccination compliance among newly employed doctors and nurses was 54%. Active interventions such as simplifying the vaccination process and frequent notifications are needed to achieve optimal immunization rates. [ABSTRACT FROM AUTHOR]

• Worldwide, the 61% of all healthcare workers agree with mandatory flu vaccination. • Great heterogeneity exists, with differences between continents and professionals. • Vaccinated healthcare workers agree more frequently with mandatory flu vaccination. • Few studies investigate mandatory vaccination agreement as the main outcome. Influenza is a disease responsible for thousands of deaths every year. Although healthcare workers (HCWs) represent a way of contagion for patients, vaccination coverage among them is low. Mandatory vaccination has been proposed, but controversies remain. This systematic review and meta-analysis aimed to assess the acceptance of mandatory vaccination by HCWs, and to investigate associated characteristics. MEDLINE, Scopus, Embase, PsycInfo, CINAHL and Web of Science were used to search for studies assessing the topic. PRISMA statements were followed. Of the 13,457 univocal records found, 52 studies were included in the systematic review and 40 in the meta-analysis. The pooled proportion of HCWs accepting the policy was of 61% (95% CI: 53%- 68%) but with great heterogeneity between continents (from 54% in Europe to 69% in Asia) and in different professionals (from 40% in nurses to 80% in students). Vaccinated HCWs agreed more frequently with mandatory vaccination than non-vaccinated ones. More studies that consider mandatory vaccination acceptance as the main outcome are needed, but the results of this study confirm that in some settings the majority of HCWs favour mandatory vaccination. This, combined with effects that a flu epidemic could have if overlapped to pandemics with similar symptoms, requires renewed considerations on mandatory vaccination. [ABSTRACT FROM AUTHOR]

• First study among primary health workers and vaccine hesitancy in Croatia. • One in six HCWs respondents demonstrated hesitancy towards vaccination. • Vaccine hesitancy is more pronounced in nurses compared to physicians. • Observed severe side effects is associated with vaccine hesitancy. Primary health care workers (HCWs) provide almost all vaccine services in Croatia, so they play an essential role in vaccine recommendations and uptake. The aim of this study was to determine the level of vaccine hesitancy among primary HCWs, to identify differences between nurses and physicians in attitudes, beliefs and behaviours towards vaccination, and to determine predictors of vaccine hesitancy among HCWs. We conducted a cross-sectional study from July to December in 2018 among physicians and nurses employed in the services of epidemiology, public health, school medicine, pediatrics and general practice/family medicine in Primorje-Gorski Kotar County, a primarily urban region with a population around 300 000 in the northern part of Croatia. The list of primary HCWs offices was obtained from the Croatian Health Insurance Fond website. We used a self-administered questionnaire on their attitudes, beliefs and behaviours relative to vaccination. Obtained response rate was 65.5% (324/495) of eligible primary HCWs; 64.1% (143/223) of physicians and 66.5% (181/272) of nurses. Seventeen percent of HCWs were identified as vaccine hesitant, and in univariate analysis, we observed an association between HCWs occupation and their own vaccination against flu (p = 0.001), measles (p = 0.016) and HPV (p = 0.025). Nurses and physicians differed (p < 0.001) in their general attitude, beliefs and behaviours towards vaccination, with a higher level of hesitancy among nurses. In multiple logistic regression, those more likely to be vaccine-hesitant were nurses (AOR = 5.73, 95%CI = 2.48–13.24), those who were uncertain or would never receive a vaccine against measles (AOR=11.13; 95%CI=5.37–23.10) and HPV (AOR=5.02; 95%CI=2.60–9.74), as well as those who had encountered a serious adverse event following immunization (AOR=7.55; 95%CI=3.13–19.18). As personal hesitancy may have a negative impact on vaccination education and recommendations, and therefore vaccine coverage, it is necessary to implement interventions to increase vaccination knowledge and confidence among primary health care workers, especially nurses. [ABSTRACT FROM AUTHOR]

Importance: Healthcare personnel (HCP) are important messengers for promoting vaccines, for both adults and children. Our investigation describes perceptions of fully vaccinated HCP about COVID-19 vaccine for themselves and primary series for their children., Objective: To determine associations between sociodemographic, employment characteristics and perceptions of COVID-19 vaccines among HCP overall and the subset of HCP with children, who were all mandated to receive a COVID-19 vaccine, in a large US metropolitan region., Design: Cross-sectional survey of fully vaccinated HCP from a large integrated health system., Setting: Participants were electronically enrolled within a multi-site NYS healthcare system from December 21, 2021, to January 21, 2022., Participants: Of 78,000 employees, approximately one-third accessed promotional emails; 6,537 employees started surveys and 4165 completed them. Immunocompromised HCP (self-reported) were excluded., Exposure(s) (for Observational Studies): We conducted a survey with measures including demographic variables, employment history, booster status, child vaccination status; vaccine recommendation, confidence, and knowledge., Main Outcome(s) and Measures: The primary outcome was COVID-19 vaccine hesitancy for all dose types - primary series or booster doses - among HCP., Results: Findings from 4,165 completed surveys indicated that almost 17.2 % of all HCP, including administrative and clinical staff, were hesitant or unsure about receiving a COVID-19 vaccine booster, despite the NYS recommendation to do so. Depending on age group, between 20 % and 40 % of HCP were hesitant about having their children vaccinated for COVID-19, regardless of clinical versus non-clinical duties. In multivariable regression analyses, lack of booster dose, unvaccinated children, females, income less than $50,000, and residence in Manhattan remained significantly associated with vaccine hesitancy., Conclusions and Relevance: Despite mandated COVID-19 vaccination, a substantial proportion of HCP remained vaccine hesitant towards adult booster doses and pediatric COVID-19 vaccination. While provider recommendation has been the mainstay of combatting COVID-19 vaccine hesitancy, a gap exists between HCP-despite clinical or administrative status-and the ability to communicate the need for vaccination in a healthcare setting. While previous studies describe the HCP vaccine mandate as a positive force to overcome vaccine hesitancy, we have found that despite a mandate, there is still substantial COVID-19 vaccine hesitancy, misinformation, and reluctance to vaccinate children., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Mundeep K. Kainth reports statistical analysis and writing assistance were provided by This work was supported by grant R24AG064191 from the National Institute on Aging of the National Institutes of Health. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier India Pvt Ltd. All rights reserved.)

Healthcare providers (HCP) are seen by the public as the most trustworthy source of information about vaccination. While HCPs could be a valuable partner to increase vaccine confidence in general, it is not clear whether they feel confident themselves to address questions concerning vaccination. In the context of the EU Joint Action on Vaccination (EU-JAV), the Vaccine Training Barometer, an online survey tool, was developed to assess how frequently HCPs receive questions about vaccination, how confident they feel to answer these questions, and to what extent they are willing to follow extra training. After a pilot test in Flanders, Belgium, the Barometer was launched and completed by 833 HCPs in Flanders and 291 HCPs in the Spanish regions of Catalonia, Navarre and Valencian Community from November 2020 until January 2021, during the COVID-19 pandemic, just before and during the start of the first COVID-19 vaccination campaigns. In both countries, HCPs frequently received questions about vaccination (mostly on a daily or weekly basis), and about two thirds of them indicated that the frequency of questions had increased during the three months prior to completing the survey. Most questions were about the side effects and safety of vaccines. In both countries, a considerable proportion of HCPs did not feel confident to answer vaccine-related questions (31.5% felt confident in Flanders, 21.6% in Spain). A large proportion of HCPs received questions in the last three months before the survey that they could not answer (52.4% of respondents in Flemish sample, 41.5% in Spanish sample). Only 11.4% (Flanders) and 11.3% (Spain) of the respondents felt they gained sufficient knowledge through their standard education to be able to answer questions about vaccination. Almost all respondents were willing to follow extra training on vaccination (Flanders: 95.4%, Spain: 96.6%). The Vaccine Training Barometer is thus a useful tool to monitor HCPs' confidence to answer questions about vaccination and to capture their training needs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Introduction: The live-attenuated vaccines Bacillus Calmette-Guérin (BCG) and Vaccinia have been associated with beneficial non-specific effects. We assessed the prevalence of BCG and Vaccinia vaccine scars in a cohort of Danish health care workers and investigated the association between the presence of vaccine scars and self-reported chronic diseases., Methods: Cross-sectional study utilizing baseline data collected during 2020-2021 at enrollment in a BCG trial aiming to assess the effect of BCG vaccination on absenteeism and infectious disease morbidity during the SARS-COV-2 pandemic. In Denmark, Vaccinia was discontinued in 1977, and BCG was phased out in the early 1980s. We used logistic regression analysis (adjusted for sex, birth year, and smoking status) to estimate the association between scar status and chronic diseases, providing adjusted Odds Ratios (aORs) with 95 % Confidence Intervals, for participants born before 1977, and born from 1965 to 1976., Results: The cohort consisted of 1218 participants (206 males; 1012 females) with a median age of 47 years (Q1-Q3: 36-56). Among participants born 1965-1976 (n = 403), who experienced the phase-outs, having BCG and/or Vaccinia scar(s) vs. having no vaccine scars yielded an aOR of 0.51 (0.29-0.90) of self-reported chronic disease; an effect primarily driven by BCG. In the same birth cohort, having vaccine scar(s) was most strongly associated with a lower prevalence of chronic respiratory and allergic diseases; the aORs being 0.39 (0.16-0.97) and 0.39 (0.16-0.91), respectively., Conclusion: Having a BCG scar was associated with a lower prevalence of self-reported chronic disease., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

• Vaccine safety was two times more important than vaccine efficacy for determining vaccination. • Arranging vaccination by "walk-in" can increase the vaccination uptake rate by over 50%. • Implementing mobile vaccination stations can increase the vaccination uptake by over 40%. This study examined the relative importance of factors relating to vaccine characteristics, social normative influence and convenience in access to vaccine for determining decision making for seasonal influenza vaccination (SIV) among healthcare personnel (HCP), aiming to optimize existing influenza vaccination programmes for HCP. A discrete choice experiment (DCE) was conducted in HCP working in public hospitals in Hong Kong. The DCE was designed to examine the relative importance of vaccine characteristics (vaccine efficacy and safety), social normative influence reflected by the proportion of HCP colleagues intending to take SIV, and convenience in access to vaccine indicated by vaccination programme duration, vaccination location, vaccination arrangement procedure and service hours in determining influenza vaccination choice among HCP. Mixed logit regression modelling was conducted to examine the preference weight (β) of factors included in the DCE for determining vaccination choice. Vaccination probability increased with increase in vaccine efficacy (β = 0.02 for per 1% increase), vaccination location changing from "designated staff clinic" to "mobile station" (β = 0.37), vaccination arrangement procedure changing from "by appointment" to "by walk-in" (β = 0.99), but decreased with the increase in probability of mild reactions to vaccination (β = −0.05 for per 1% increase). Vaccine safety was judged to be more important than vaccine efficacy for determining vaccination choice. Arranging vaccination service by walk-in and implementing mobile vaccination station should be considered in future SIV programmes to compensate for the effect of perceived low vaccination efficacy and concerns about vaccine safety to promote SIV uptake among HCP. [ABSTRACT FROM AUTHOR]

The Sisonke 2 study provided a homologous boost at least 6 months after administration of the priming dose of Ad26.COV2.S for healthcare workers enrolled on the Sisonke phase 3b implementation study. Safety monitoring was via five reporting sources: (i.) self-report through a web-link; (ii.) paper-based case report forms; (iii.) a toll-free telephonic reporting line; (iv.) healthcare professionals-initiated reports; and (v.) active linkage with National Disease Databases. A total of 2350 adverse events were reported by 2117 of the 240 888 (0.88%) participants enrolled; 1625 of the 2350 reported events are reactogenicity events and 28 adverse events met seriousness criteria. No cases of thrombosis with thrombocytopaenia syndrome were reported; all adverse events including thromboembolic disorders occurred at a rate below the expected population rates apart from one case of Guillain Barre Syndrome and one case of portal vein thrombosis. The Sisonke 2 study demonstrates that two doses of Ad26.COV2.S is safe and well tolerated; and provides a feasible model for national pharmacovigilance strategies for low- and middle-income settings., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Introduction: Healthcare workers (HCWs) from an interprovincial Canadian cohort gave serial blood samples to identify factors associated with anti-receptor binding domain (anti-RBD) IgG response to the SARS-CoV-2 virus., Methods: Members of the HCW cohort donated blood samples four months after their first SARS-CoV-2 immunization and again at 7, 10 and 13 months. Date and type of immunizations and dates of SARS-CoV-2 infection were collected at each of four contacts, together with information on immunologically-compromising conditions and current therapies. Blood samples were analyzed centrally for anti-RBD IgG and anti-nucleocapsid IgG (Abbott Architect, Abbott Diagnostics). Records of immunization and SARS-CoV-2 testing from public health agencies were used to assess the impact of reporting errors on estimates from the random-effects multivariable model fitted to the data., Results: 2752 of 4567 vaccinated cohort participants agreed to donate at least one blood sample. Modelling of anti-RBD IgG titer from 8903 samples showed an increase in IgG with each vaccine dose and with first infection. A decrease in IgG titer was found with the number of months since vaccination or infection, with the sharpest decline after the third dose. An immunization regime that included mRNA1273 (Moderna) resulted in higher anti-RBD IgG. Participants reporting multiple sclerosis, rheumatoid arthritis or taking selective immunosuppressants, tumor necrosis factor inhibitors, calcineurin inhibitors and antineoplastic agents had lower anti-RBD IgG. Supplementary analyses showed higher anti-RBD IgG in those reporting side-effects of vaccination, no relation of anti-RBD IgG to obesity and lower titers in women immunized in early or mid-pregnancy. Sensitivity analysis results suggested no important bias in the self-report data., Conclusion: Creation of a prospective cohort was central to the credibility of results presented here. Serial serology assessments, with longitudinal analysis, provided effect estimates with enhanced accuracy and a clearer understanding of medical and other factors affecting response to vaccination., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Nicola Cherry reports financial support was provided by Canadian Institutes of Health Research. Nicola Cherry reports financial support was provided by Canadian Immunology Task Force. Nicola Cherry reports financial support was provided by College of Physicians and Surgeons of Alberta., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Introduction: The rapid development of COVID-19 vaccines is a cornerstone in the global effort to combat the pandemic. Healthcare workers (HCWs), being at the forefront of the pandemic response, have been the focus of vaccine mandate policies. This review aims to evaluate the impacts of COVID-19 vaccine mandates among HCWs, a critical step in understanding the broader implications of such policies in healthcare settings., Objective: The review seeks to synthesize available literature to contribute to greater understanding of the outcomes associated with COVID-19 vaccine mandates for HCWs including vaccine uptake, infection rates, and staffing., Methods: A systematic search of relevant literature published from March 2020 to September 2023 was conducted. The Newcastle-Ottawa scale was employed for quality assessment of the included articles. A total of 4,779 publications were identified, with 15 studies meeting the inclusion criteria for the review. A narrative synthesis approach was used to analyze these studies., Results: COVID-19 vaccine mandates for HCWs were broadly successful in increasing vaccine uptake in most settings. Although the penalties imposed on unvaccinated HCWs did not lead to major disruption of health services, less well-resourced areas may have been more impacted. Furthermore, there is insufficient literature on the impact of the vaccine mandate on reducing SARS-CoV-2 infection among HCWs., Conclusion: COVID-19 vaccine mandates for HCWs have significant implications for public health policy and healthcare management. The findings underscore the need for tailored approaches in mandate policies, considering the specific contexts of healthcare settings and the diverse populations of HCWs. While mandates have shown potential in increasing vaccine uptake with minimal impacts to staffing, more work is needed to investigate the impacts of mandates across various contexts. In addition to these impacts, future research should focus on long-term effects and implications on broader public health strategies., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Arnold Okpani reports financial support was provided by International Development Research Centre. Arnold Okpani reports financial support was provided by Canadian Institutes of Health Research. Karen Lockhart reports financial support was provided by Canadian Institutes of Health Research. Annalee Yassi reports financial support was provided by Canadian Institutes of Health Research. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Healthcare workers (HCW) are at risk of contracting vaccine-preventable diseases and spreading these infections to their patients. Vaccination against preventable diseases prior to clinical training can mitigate this risk. Accreditation guidance can be used as an opportunity to enforce desirable norms and standards. Standards from 144 national accreditation organizations spanning 123 member states listed in the Directory of Organizations that Recognize/Accredit Medical Schools by the Foundation for Advancement of International Medical Education and Research were reviewed and summarized. Findings were further stratified by World Bank income group and WHO region. While higher-income countries were more likely to have accreditation guidelines available than lower- or middle-income countries, few national medical school accreditation bodies specifically request immunization status of trainees as a standard. Further, almost none mention specific antigens for which immunity should be assessed. These findings should be used by medical school and other health professional training accreditation bodies to inform future policy direction to protect trainees as future HCW., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Gabriel Gaviola reports financial support was provided by World Health Organization., (Copyright © 2023. Published by Elsevier Ltd.)

Introduction: Borno state in north-eastern Nigeria is the epicentre of the >10 years' insurgency activities that have affected the region since 2009, resulting in the destruction of health facilities, killing of health workers, massive population displacement and lack of access to populations to provide health services. This article demonstrates how the involvement of community informants from insecure areas (CIIA) to conduct polio surveillance in security-challenged settlements of Borno state contributed to the expansion of polio surveillance reach beyond polio vaccination reach., Method: In each of the 19 security compromised Local Government areas (LGAs) with community informants from insecure areas, Android phones enabled with Vaccination Tracking System (VTS) technology and Open Data Kit (ODK) mobile application were provided to capture geo-coordinates as evidence (geo evidence) for polio surveillance activity conducted. These geo evidence captured were uploaded and mapped to show insecure settlements reached with polio surveillance and those yet to be reached., Results: A total of 3183 security compromised settlements were reached for polio surveillance between March 2018 and October 2019 with valid geo evidence, 542 of these security-compromised settlements had not been previously reached by any other intervention for polio surveillance or polio vaccination., Conclusion: The capturing of geo-coordinates as a proxy indicator of polio surveillance activity conducted by informants provided significant evidence of settlements reached for sustained polio surveillance even when a case of Acute Flaccid Paralysis (AFP) had not been reported from these settlements. Using the geo evidence captured by CIIA in insecure settlements, we have demonstrated the expansion of polio surveillance reach beyond polio vaccination reach in Borno state., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Background: The long-term retention of information disclosed during the informed consent in clinical trials lasting over a year cannot be guaranteed for all volunteers. This study aimed to assess the level of participants' retention and understanding of the trial information after two years of participation in a vaccine trial., Methods: In total, 699 health care providers (HCPs) and frontline workers were enrolled in the EBL2007 vaccine trial conducted between February 2019 and September 2022 in the Health District of Boende, Democratic Republic of the Congo (DRC). Individual scores obtained from a questionnaire (test of understanding, TOU), specifically designed to assess the understanding of the consent at baseline, were collected before the clinical trial started and at one-year and two-year intervals., Results: TOU scores were high in the beginning of the trial (median TOU = 10/10), but significantly decreased in both the first and second years following (median TOU = 8/10 in year 1 and median TOU = 9/10 in year 2, p-value < 0.0001). The decrease in scores was significantly higher among individuals with occupations requiring shorter education such as midwives (median TOU = 7/10 in year 1 and 8/10 in year 2, pvalue = 0.025). Furthermore, older participants exhibited poorer retention of information compared to younger individuals (median TOU = 8/10 vs 9/10, p-value = 0.007)., Conclusion: We observed a significant decline in the informational knowledge of informed consent, specifically in terms of basic knowledge on the study vaccine and trial procedures. As participant safety and understanding is a paramount ethical concern for researchers, it is crucial for participants to fully comprehend the study's objectives and potential risks. Therefore, our findings suggest the need for clinical researchers to re-explain participants to optimize the protection of their rights and wellbeing during the research., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Potential conflicts of interest All authors attest they meet the ICMJE criteria for authorship., (Copyright © 2023. Published by Elsevier Ltd.)

Highlights • Few studies evaluated Tdap coverage among healthcare workers. • From 28 studies, initial Tdap coverage ranged from 6.1% to 45.1%. • Immunization with other vaccines was positively associated with Tdap uptake. • Two intervention studies implemented mandatory vaccination and three educational strategies. Abstract During the last decades pertussis incidence raised globally. Several vaccination strategies targeting adults to reduce pertussis among young infants have been proposed, including vaccination of healthcare workers (HCWs). The aim of this study was to analyse, by performing a systematic review of literature, published papers that evaluated Tdap coverage among HCWs, variables associated with vaccine uptake and efforts implemented to raise vaccination rates. We searched the MedLine, Embase, SCOPUS, LILACS, Web of Science and Cochrane for full-text studies that evaluated Tdap coverage in HCW. Two independent reviewers screened the articles and extracted the data. Twenty-eight studies published from 2009 to 2018 were reviewed. Most studies were conducted in the USA. Initial Tdap coverage varied from 6.1% to 63.9%. USA and France are the only two countries with studies evaluating Tdap coverage within HCWs using national data. In the USA, Tdap coverage in HCWs raised from 6.1% to 45.1% from 2007 to 2015. In the analysis of French national data, a Tdap coverage of 63.9% was observed. Five studies used interventions to raise Tdap coverage in HCWs. Two intervention studies implemented mandatory vaccination and three used educational strategies. All of them achieved coverages over 86%. Only eleven studies analysed the association of Tdap vaccination with variables of interest. Previous immunization with other vaccines recommended for HCWs (like influenza, hepatitis B and MMR) was positively associated with Tdap uptake in four studies. In conclusion, overall Tdap coverage among HCWs is low, but seems to increase over the years after the vaccine introduction and with implementation of interventions to increase coverage. [ABSTRACT FROM AUTHOR]