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Bordetella pertussis, which causes a respiratory disease known as pertussis ("whooping cough") remains an important global challenge, with the incidence in pertussis cases increasing in recent years. Newborns and infants are at increased risk for severe morbidity and mortality from this bacterium. Vaccination in pregnancy has become an important strategy to both passively transfer immunity as well as prevent infection in pregnant persons, who are a major source of newborn infection, thus attempting to decrease the impact of this serious disease. It is considered safe for the pregnant person, the developing fetus, and the infant, and during the first 3 months of life it has been shown to be highly effective in preventing pertussis. There are a variety of strategies, recommendations, and adherence rates associated with pertussis vaccination in pregnancy around the world. We summarize the 2021 Global Pertussis Initiative Annual Meeting that reviewed the current global status of pertussis vaccination in pregnancy and remaining medical and scientific questions, with a focus on vaccination challenges and strategies for obstetric and gynecologic healthcare providers., (© 2024 International Federation of Gynecology and Obstetrics.)

Importance: Seasonal influenza vaccination in pregnancy can reduce influenza illness among pregnant women and newborns. Evidence is limited on whether seasonal influenza vaccination in pregnancy is associated with adverse childhood health outcomes., Objective: To assess the association between maternal influenza vaccination during pregnancy and early childhood health outcomes., Design, Setting, and Participants: Retrospective cohort study, using a birth registry linked with health administrative data. All live births in Nova Scotia, Canada, between October 1, 2010, and March 31, 2014, were included, with follow-up until March 31, 2016. Adjusted hazard ratios (HRs) and incidence rate ratios (IRRs) with 95% confidence intervals were estimated while controlling for maternal medical history and other potential confounders using inverse probability of treatment weighting., Exposures: Seasonal influenza vaccination during pregnancy., Main Outcomes and Measures: Childhood outcomes studied were immune-related (eg, asthma, infections), non-immune-related (eg, neoplasms, sensory impairment), and nonspecific (eg, urgent or inpatient health care utilization), measured from emergency department and hospitalization databases., Results: Among 28 255 children (49% female, 92% born at ≥37 weeks' gestation), 10 227 (36.2%) were born to women who received seasonal influenza vaccination during pregnancy. During a mean follow-up of 3.6 years, there was no significant association between maternal influenza vaccination and childhood asthma (incidence rate, 3.0 vs 2.5 per 1000 person-years; difference, 0.53 per 1000 person-years [95% CI, -0.15 to 1.21]; adjusted HR, 1.22 [95% CI, 0.94 to 1.59]), neoplasms (0.32 vs 0.26 per 1000 person-years; difference, 0.06 per 1000 person-years [95% CI, -0.16 to 0.28]; adjusted HR, 1.26 [95% CI, 0.57 to 2.78]), or sensory impairment (0.80 vs 0.97 per 1000 person-years; difference, -0.17 per 1000 person-years [95% CI, -0.54 to 0.21]; adjusted HR, 0.82 [95% CI, 0.49 to 1.37]). Maternal influenza vaccination in pregnancy was not significantly associated with infections in early childhood (incidence rate, 184.6 vs 179.1 per 1000 person-years; difference, 5.44 per 1000 person-years [95% CI, 0.01 to 10.9]; adjusted IRR, 1.07 [95% CI, 0.99 to 1.15]) or with urgent and inpatient health services utilization (511.7 vs 477.8 per 1000 person-years; difference, 33.9 per 1000 person-years [95% CI, 24.9 to 42.9]; adjusted IRR, 1.05 [95% CI, 0.99 to 1.16])., Conclusions and Relevance: In this population-based cohort study with mean follow-up duration of 3.6 years, maternal influenza vaccination during pregnancy was not significantly associated with an increased risk of adverse early childhood health outcomes.

Sentinel surveillance of acute hospitalisations in response to infectious disease emergencies such as the 2009 influenza A(H1N1)pdm09 pandemic is well described, but recognition of its potential to supplement routine public health surveillance and provide scalability for emergency responses has been limited. We summarise the achievements of two national paediatric hospital surveillance networks relevant to vaccine programmes and emerging infectious diseases in Canada (Canadian Immunization Monitoring Program Active; IMPACT from 1991) and Australia (Paediatric Active Enhanced Disease Surveillance; PAEDS from 2007) and discuss opportunities and challenges in applying their model to other contexts. Both networks were established to enhance capacity to measure vaccine preventable disease burden, vaccine programme impact, and safety, with their scope occasionally being increased with emerging infectious diseases' surveillance. Their active surveillance has increased data accuracy and utility for syndromic conditions (e.g. encephalitis), pathogen-specific diseases (e.g. pertussis, rotavirus, influenza), and adverse events following immunisation (e.g. febrile seizure), enabled correlation of biological specimens with clinical context and supported responses to emerging infections (e.g. pandemic influenza, parechovirus, COVID-19). The demonstrated long-term value of continuous, rather than incident-related, operation of these networks in strengthening routine surveillance, bridging research gaps, and providing scalable public health response, supports their applicability to other countries.

BackgroundThe Canadian National Vaccine Safety (CANVAS) network monitors the safety of seasonal influenza vaccines in Canada.AimTo provide enhanced surveillance for seasonal influenza and pandemic influenza vaccines.MethodsIn 2017/18 and 2018/19 influenza seasons, adults (≥ 15 years of age) and parents of children vaccinated with the seasonal influenza vaccine participated in an observational study using web-based active surveillance. Participants completed an online survey for health events occurring in the first 7 days after vaccination. Participants who received the influenza vaccine in the previous season, but had not yet been vaccinated for the current season, were unvaccinated controls.ResultsIn 2017/18, 43,751 participants and in 2018/19, 47,798 completed the online safety survey. In total, 957 of 30,173 participants vaccinated in 2017/18 (3.2%; 95% confidence interval (CI): 3.0-3.4) and 857 of 25,799 participants vaccinated in 2018/19 (3.3%; 95% CI: 3.1-3.5) reported a health problem of sufficient intensity to prevent their normal daily activities and/or cause them to seek medical care (including hospitalisation). This compared to 323 of 13,578 (2.4%; 95% CI: 2.1-2.6) and 544 of 21,999 (2.5%; 95% CI: 2.3-2.7) controls in each respective season. The event rate in vaccinated adults and children was higher than the background rate and was associated with specific influenza vaccines. The higher rate of events was associated with systemic symptoms and migraines/headaches.ConclusionIn 2017/18 and 2018/19, higher rates of events were reported following seasonal influenza vaccination than in the pre-vaccination period. This signal was associated with several seasonal influenza vaccine products.

Background: In children with epilepsy, fever and illness are known triggers for seizure; therefore, clinicians and parents could be concerned that immunization-induced inflammation and fever could also trigger seizures. We sought to estimate the risk of emergency department (ED) visit or hospitalization for epilepsy/seizure and all causes after immunization in children younger than 7 years of age with epilepsy., Methods: We conducted a self-controlled case series of children diagnosed with epilepsy before their 7th birthday and immunized from 2005 to 2015 in Ontario (population 14.2 million) and Manitoba (population 1.3 million), Canada, using administrative healthcare data. We estimated the age- and season-adjusted relative incidence (aRI) of epilepsy/seizure-related and all-cause ED visits/hospitalizations during various risk periods 0-28 days after inactivated and live immunizations versus a control period 35-83 days postimmunization. Estimates from each province were analyzed separately and then combined in a random-effects meta-analysis., Results: The combined risk of epilepsy/seizure-related hospitalization/ED visit was increased 0-2 days after inactivated vaccines (aRI = 1.5, 95% confidence interval: 1.1-1.9) and 7-10 days after live vaccines (aRI = 1.9, 1.4-2.7). For all-cause ED visit/hospitalization, the combined aRI estimate was 0.9 (0.8-1.2) 0-2 days after inactivated vaccines and 1.3 (1.1-1.5) 7-10 days after live vaccines., Conclusions: The risk of epilepsy/seizure-related ED visit/hospitalization was modestly increased among children with epilepsy during peak periods of fever and inflammation following inactivated and live vaccines. These risks must be balanced against the risk of complications from vaccine-preventable diseases.

Background: In children with epilepsy, fever and infection can trigger seizures. Immunization can also induce inflammation and fever, which could theoretically trigger a seizure. The risk of seizure after immunization in children with pre-existing epilepsy is not known. The study objective was to determine the risk of medically attended seizure after immunization in children with epilepsy < 7 years of age., Methods: We conducted a retrospective study of children < 7 years of age with epilepsy in Nova Scotia, Canada from 2010 to 2014. Hospitalizations, emergency visits, unscheduled clinic visits, and telephone calls for seizures were extracted from medical records. Immunization records were obtained from family physicians and Public Health with informed consent. We conducted a risk interval analysis to estimate the relative risk (RR) of seizure during risk periods 0-14, 0-2, and 5-14 days post-immunization versus a control period 21-83 days post-immunization., Results: There were 302 children with epilepsy who were eligible for the study. Immunization records were retrieved on 147 patients (49%), of whom 80 (54%) had one or more immunizations between the epilepsy diagnosis date and age 7 years. These 80 children had 161 immunization visits and 197 medically attended seizures. Children with immunizations had more seizures than either those with no immunizations or those with no records (mean 2.5 versus 0.7 versus 0.9, p < 0.001). The risk of medically attended seizure was not increased 0-14 days after any vaccine (RR = 1.1, 95% confidence interval (CI): 0.5-2.8) or 0-2 days after inactivated vaccines (RR = 0.9, 95% CI: 0.1-7.1) versus 21-83 days post-immunization. No seizure events occurred 5-14 days after live vaccines., Conclusions: Children with epilepsy do not appear to be at increased risk of medically attended seizure following immunization. These findings suggest that immunization is safe in children with epilepsy, with benefits outweighing risks.

Background: The Canadian Adverse Event Following Immunization Surveillance System (CAEFISS) receives reports via active syndromic surveillance for selected serious AEFI from the Canadian Immunization Monitoring Program Active (IMPACT) and via targeted passive surveillance from Federal/Provincial/Territorial health jurisdictions. Post-immunization seizure is a target of active and passive surveillance. Since 2009, the revised national AEFI reporting forms enable capture of terms specific to several Brighton Collaboration Case Definitions (BCCD) including generalized seizure and fever., Objective: To evaluate feasibility of applying the BCCD for generalized seizure to adverse event following immunization (AEFI) reports collected by IMPACT and targeted passive surveillance (non-IMPACT)., Methods: Reports to CAEFISS coded as seizure in children <2 years of age (vaccination dates 1998-2011) were reviewed retrospectively. A BCCD level (1-5 or unclassifiable) was assigned. The effects of reporting source (IMPACT versus non-IMPACT), seriousness [serious (e.g., hospitalized) versus non-serious], vaccination year (1998-2008 versus 2009-2011), and data submission method to CAEFISS (electronic versus paper) were assessed by stratified analysis., Results: There were 459 IMPACT and 908 non-IMPACT cases analyzed, of which 99.6% and 27%, respectively, were serious reports. The revised reporting form that captured the BCCD components (2009-2011) was associated with increased proportions of IMPACT and non-IMPACT cases meeting the BCCD for generalized seizure., Conclusions: Incorporating the BCCD components (level of consciousness, motor manifestations and fever ≥38°C) into the national reporting form and guidelines appeared to improve the feasibility of their use in AEFI surveillance. This effect was more pronounced among active syndromic surveillance compared to targeted passive surveillance reports., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Healthcare workers' (HCWs) knowledge, attitudes, and beliefs regarding pertussis immunization were assessed and compared to the rate of vaccine uptake. A questionnaire was distributed to employees at a paediatric and maternity tertiary care centre. Respondents were then offered a dose of the tetanus, diphtheria, and acellular pertussis vaccine (Tdap) at a free vaccine clinic. In total, 529 out of 3051 (17%) employees completed the survey and 61 received the Tdap vaccine. Although 76% of participants were willing to be immunized, only 15% presented to the clinic. There is a widespread acceptance of pertussis immunization among paediatric HCWs. Stated intentions may be poorly predictive of behaviour. Education and institutional or public funding may improve vaccine uptake., (Copyright 2010. Published by Elsevier Ltd.)

Background: Live attenuated varicella vaccine (LAVV) has historically been contraindicated in children who are immunocompromised due to solid organ transplant (SOT) because of safety concerns. Recently, clinical guidelines were developed that support post‐transplant varicella vaccination in selected SOT recipients based on emerging evidence of LAVV safety. This qualitative study sought to explore barriers and facilitators to implementing the new guidelines, as well as acceptability of LAVV among healthcare providers (HCPs) and parents. Methods: HCPs and parents of transplant recipients were recruited from four sites using purposive sampling. Data from semi‐structured interviews were analyzed using an Interpretive Description approach that incorporated data from the interviews, academic knowledge and clinical experience, and drew from Grounded Theory and Thematic Analysis. The theoretical framework used was Adaptive Leadership. Results: Thirty‐four participants (16 HCPs and 18 parents) were included in the analysis. Parents developed skills in adaptive leadership that included strategies to protect their child against infectious diseases. Foundational information that live vaccines were absolutely contraindicated post‐transplant "stuck" with parents and led them to develop strategies other than vaccination to keep their child safe. Some parents struggled to understand that information previously presented as a certainty (contraindication of LAVV) could change. Their approach to adaptive leadership informed their appraisal of the new vaccination guidelines and willingness to accept vaccination. Conclusions: HCPs should adopt a family‐centered approach to communicating changing guidelines that considers parents' approach to adaptive leadership and discusses the changing nature of medical evidence. Trust between HCPs and parents can facilitate these conversations. [ABSTRACT FROM AUTHOR]

Vaccines have had a tremendous impact on reducing the burden of infectious diseases; however, they have the potential to cause adverse events following immunization (AEFIs). Prelicensure clinical trials are limited in their ability to detect rare AEFIs that may occur in less than one per thousand individuals. While postmarketing surveillance systems have shown COVID‐19 mRNA vaccines to be safe, they led to the identification of rare cases of myocarditis and pericarditis after COVID‐19 vaccination that were not initially detected in clinical trials. In this narrative review, we highlight concepts of vaccine pharmacovigilance during mass vaccination campaigns and compare the approaches used in the context of myocarditis and pericarditis following COVID‐19 vaccination to historical examples. We describe mechanisms of passive and active surveillance, their strengths and limitations, and how they interacted to identify and characterize the safety signal of myocarditis and pericarditis after COVID‐19 mRNA vaccination. Articles were synthesized from a PubMed search using relevant keywords for articles published on vaccine surveillance systems and myocarditis and pericarditis after COVID‐19 vaccination, as well as the authors' collections of relevant publications and grey literature reports. The global experience around the identification and monitoring of myocarditis and pericarditis after COVID‐19 mRNA vaccination has provided important lessons for vaccine safety surveillance and highlighted its importance in maintaining public trust in mass vaccination programmes in a pandemic context. [ABSTRACT FROM AUTHOR]

The Canadian National Vaccine Safety Network (CANVAS) conducted active participant-based surveillance for adverse events following immunization during the COVID-19 vaccine campaign. This study evaluated the association between COVID-19 vaccination and neurological adverse events. Participants were invited to complete online surveys to report health events that prevented daily activities and/or required medical attention within 7 days after COVID-19 vaccination or 7 days prior to the survey (unvaccinated controls); follow-up surveys were sent 7 months later. Neurological events were health events where the most severe symptom reported was ≥1 of: numbness/tingling, loss of taste or smell, vision loss, facial weakness/paralysis, seizure, weakness/paralysis of arms or legs, confusion, change in personality or behavior, or difficulty with urination or defecation. Data were extracted from the CANVAS-COVID database for analysis. Completed survey responses were received from 15,273 unvaccinated controls, 758,619 dose 1 recipients, 406,884 dose 2 recipients, and 126,586 dose 3 recipients. Rates of neurological events ranged from 15.9 (95 % CI 13.6–18.4) per 10,000 dose 1 ChAdOx1 recipients to 8.4 (6.5–10.8) and 7.9 (5.7–11.0) per 10,000 dose 3 mRNA-1273 and BNT162b2 recipients, respectively. Multivariable regression adjusted for age, sex, previous SARS-CoV-2 infection, and baseline health status showed an increased risk of neurological event among ChAdOx1 dose 1 recipients versus controls (adjusted OR 2.3, 95 % CI 1.2–4.3), but not among mRNA vaccine recipients after any dose. Risk of anaesthesia/paresthesia were increased following ChAdOx1 dose 1 (aOR 4.7, 1.7–13.1), and consistently but not statistically significantly higher following any dose of either mRNA vaccine. Risk of loss of smell/taste was decreased among recipients of any dose of either mRNA vaccine versus controls. The results support the safety of COVID-19 vaccines while confirming reported associations between ChAdOx1 dose 1 and neurological events. Participant-based AEFI surveillance is a useful component of post-market surveillance programs. • Active participant-based surveillance was conducted to monitor COVID-19 vaccine safety. • Neurological symptoms were not increased after mRNA-1273 and BNT162b2 versus controls. • ChAdOx1 dose 1 was associated with a small increase in neurological symptoms. • Neurological events following COVID-19 vaccination were rare. [ABSTRACT FROM AUTHOR]

Background: The gaps in clinical trial evidence about vaccination in pregnancy have serious implications for health care worker and public misunderstandings. Contradictions between National Immunization Technical Advisory Group (NITAG) recommendations and regulatory product labeling information contribute to misinformation about vaccine safety and effectiveness. Methods: A mixed methods approach that included a stakeholder consensus decision-making workshop and a national survey of Canadian health care providers (HCPs). Results: We identified knowledge gaps and serious limitations concerning the information in vaccine product labels. Stakeholders were troubled that some HCPs rely on regulatory product labels to inform their decisions without knowing their limitations in content. Our survey showed that HCPs were uncertain about the purpose of product labels and the evidence contained in them. Over a third of respondents incorrectly thought that product labels and NITAG recommendations are based on the same evidence and that the information they contain is regularly updated. Conclusions: Applying social risk theories, we show how such gaps in information defer responsibility for decisions about disease risk and vaccine safety from regulatory agencies and vaccine manufacturers onto HCPs and their clients. This may be especially relevant for COVID-19 and other emerging vaccines that are initially authorized for conditional or emergency use, and especially in understudied populations such as pregnant people. More frequent updating and alignment of robust, unbiased, and independently reviewed clinical trial and postmarket safety and effectiveness evidence with NITAG recommendations would allay HCP and public misunderstandings. [ABSTRACT FROM AUTHOR]

Within 2 years after the start of the coronavirus disease 2019 (COVID-19) pandemic, novel severe acute respiratory syndrome coronavirus 2 vaccines were developed, rigorously evaluated in large phase 3 trials, and administered to more than 5 billion individuals globally. However, adverse events of special interest (AESIs) have been described post-implementation, including myocarditis after receipt of messenger RNA (mRNA) vaccines and thrombosis with thrombocytopenia syndrome after receipt of adenoviral vector vaccines. AESIs are rare (<1 to 10/100 000 vaccinees) and less frequent than COVID-19 complications, though they have associated morbidity and mortality. The diversity of COVID-19 vaccine platforms (eg, mRNA, viral vector, protein) and rates of AESIs both between and within platforms (eg, higher rate of myocarditis after mRNA-1273 vs BNT162b2 vaccines) present an important opportunity to advance vaccine safety science. The International Network of Special Immunization Services has been formed with experts in vaccine safety, systems biology, and other relevant disciplines to study cases of AESIs and matched controls to uncover the pathogenesis of rare AESIs and inform vaccine development. [ABSTRACT FROM AUTHOR]

Background There is no uniform guideline for postchemotherapy vaccination of children with acute lymphoblastic leukemia (ALL). We evaluated waning immunity to 14 pneumococcal serotypes, pertussis toxin (PT), tetanus toxoid (TT) and varicella, and immunogenicity of postchemotherapy diphtheria, tetanus, pertussis, hepatitis B, polio, and Haemophilus influenzae type b (DTaP-IPV-Hib) and pneumococcal vaccination among previously vaccinated children treated for ALL. Methods This was a multicenter trial of children with ALL enrolled 4–12 months postchemotherapy completion. Exclusion criteria included: infant ALL, relapsed ALL, and stem cell transplant recipients. Immunocompetent children were recruited as controls. Postchemotherapy participants received DTaP-IPV-Hib and 13-valent pneumococcal conjugate vaccine (PCV13) concurrently, followed by 23-valent pneumococcal polysaccharide vaccine (PPV23) 2 months later. Serology was measured at baseline, 2 and 12 months postvaccination. Adverse events were captured via surveys. Results At enrollment, postchemotherapy participants (n = 74) were less likely than controls (n = 78) to be age-appropriately immunized with DTaP (41% vs 89%, P  < .001) and PCV (59% vs 79%, P  = .008). Geometric mean concentrations (GMCs) to TT, PT, PCV serotypes, and varicella were lower in postchemotherapy participants than controls after adjusting for previous vaccine doses (P  < .001). Two months postvaccination, GMCs to TT, PT, and PCV serotypes increased from baseline (P  < .001 for all antigens) and remained elevated at 12 months postvaccination. Antibody levels to PPV23 serotypes also increased postvaccination (P  < .001). No serious adverse events were reported. Conclusions Children treated for ALL had lower antibody levels than controls against pneumococcal serotypes, tetanus, pertussis, and varicella despite previous vaccination. Postchemotherapy vaccination with DTaP-IPV-Hib, PCV13, and PPV23 was immunogenic and well tolerated. Children with ALL would benefit from systematic revaccination postchemotherapy. Clinical Trials Registration NCT02447718. [ABSTRACT FROM AUTHOR]

• Vaccine recommendations that differ from product information are termed "off-label" • We surveyed low-, middle- and high-income countries with immunization expert groups. • 14 of 26 countries with immunization expert groups made off-label recommendations. • Few countries had policies for off-label recommendations and regulations varied. • Standard definitions and procedures for off-label recommendations are needed globally. National Regulatory Authorities approve the indications for vaccine use in the product information. Occasionally, National Immunization Technical Advisory Groups (NITAGs) make off-label recommendations for use in different age groups, populations, and dosing schedules from the product information. We sought to determine the rationale, policies and procedures for NITAG off-label recommendations. We conducted an environmental scan of Global NITAG Network members, immunization program managers and regulators in 38 high-, middle- and low-income countries. Participants completed an online survey regarding policies, procedures, and legislation governing development of off-label recommendations. A sub-sample of respondents met for a focus group and interviews which were analyzed qualitatively. Thirty-four people responded from 26/38 (68%) countries surveyed; 76% of respondents were NITAG members or immunization program managers. Recommendations for off-label vaccine use were made in 14/26 (54%) countries; the NITAG made those recommendations in 8/14 (57%) countries. Reasons for off-label vaccine recommendations included response to disease outbreaks or vaccine shortages. Only one country had standard operating procedures for developing off-label recommendations while 6/14 (43%) countries had policies for implementing off-label recommendations. Nine respondents from 8 countries agreed to participate in a focus group (n = 6) or individual interviews (n = 3). Barriers to off-label recommendations included legal concerns, lack of standard definition for off-label use, and manufacturer reluctance to update product information. Facilitators included confidence in the decision-making process, and transparency of open communication among stakeholders. Best practice guidelines are needed that define off-label use and outline a transparent, evidence-based approach to develop off-label recommendations. [ABSTRACT FROM AUTHOR]

Background The World Health Organization's Strategic Advisory Group of Experts on Immunization has declared that maternal immunization is a key priority. Robust adverse event following immunization (AEFI) surveillance systems that capture outcomes in pregnant women and their infants are needed to ensure the safety of maternal immunization programs. We sought to identify the active and passive AEFI surveillance systems for pregnant women and their offspring described in the literature. Methods A systematic literature review was conducted of the MEDLINE, CINAHL, and EMBASE databases from 1990 to 2014. English-language articles were reviewed if they included pregnant women as the population of interest and described the surveillance method used. Results Of 619 articles retrieved from the search, 16 met the criteria for review. These included reports of AEFI surveillance for pregnant women, their offspring, or both. The majority of reports (11/16) came from the USA and described findings on two active and four passive AEFI surveillance systems, only three of which specifically targeted pregnant women. The remaining five articles described one-time AEFI surveillance programs, all in high-income countries. Conclusion There are no published reports outside of the USA of ongoing AEFI surveillance systems that specifically target pregnant women or their offspring. There may be AEFI surveillance systems that capture events in these populations that have not been reported in the literature. A survey of immunization program managers and national regulatory authorities is needed to determine the current status of AEFI surveillance for pregnant women and their offspring globally. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study examined short-to-medium term safety of COVID-19 vaccines among adults aged ≥65 years using the Canadian National Vaccine Safety Network active safety surveillance data. Both vaccinated and unvaccinated older adult participants recruited from seven provinces and territories were included in the analysis. Safety was assessed at 7 days after COVID-19 vaccination (dose 1, 2 and 3), and 7 months after dose 1. Multivariable logistic regression was used to examine the association between BNT162b2/mRNA-1273 COVID-19 vaccines and two short-term health events: 1) health event preventing daily activities and/or required medical consultation, 2) serious health events resulting in an emergency department visit and/or hospitalization within 7 days following each dose. We also assessed the rates of serious health events for the period between dose 1 and 2, and 7-months following dose 1. Between December 2020 and February 2022, a total of 173,038, 104,452, and 13,970 older adults completed dose 1, dose 2, and dose 3 surveys, respectively. The control survey was completed by 2,955 unvaccinated older adults. Health events occurred more frequently among recipients after dose 2 homologous mRNA-1273 (adjusted odds ratio [95 % confidence interval]: 2.91 [2.24–3.79]) and dose two heterologous (BNT162b2 followed by mRNA-1273): 1.50 [1.12–2.02] compared to unvaccinated counterparts. There was no difference in event rates after any dose of BNT162b2 and unvaccinated participants. The rates of serious health events following COVID-19 vaccination were very low (≤0.3 %) across all vaccine products and doses, and were not higher compared to unvaccinated controls, and were not associated with an emergency department visit or hospitalization within 7 days following vaccination. Reported symptoms were self-limited and rarely required medical assessment. Our findings further strengthen the current evidence that mRNA COVID-19 vaccines are safe and can be used to inform older adults about expected adverse events following COVID-19 vaccination. [ABSTRACT FROM AUTHOR]

Background: Pregnant individuals have been receiving COVID-19 vaccines following pre-authorisation clinical trials in non-pregnant people. This study aimed to determine the frequency and nature of significant health events among pregnant females after COVID-19 vaccination, compared with unvaccinated pregnant controls and vaccinated non-pregnant individuals.Methods: We did an observational cohort study, set in seven Canadian provinces and territories including Ontario, Quebec, British Columbia, Alberta, Nova Scotia, Yukon, and Prince Edward Island. Eligibility criteria for vaccinated individuals were a first dose of a COVID-19 vaccine within the previous 7 days; an active email address and telephone number; ability to communicate in English or French; and residence in the aforementioned provinces or territories. Study participants were pregnant and non-pregnant females aged 15-49 years. Individuals were able to participate as controls if they were unvaccinated and fulfilled the other criteria. Data were collected primarily by self-reported survey after both vaccine doses, with telephone follow-up for those reporting any medically attended event. Participants reported significant health events (new or worsening of a health event sufficient to cause work or school absenteeism, medical consultation, or prevent daily activities) occurring within 7 days of vaccination or within the past 7 days for unvaccinated individuals. We employed multivariable logistic regression to examine significant health events associated with mRNA vaccines, adjusting for age group, previous SARS-CoV-2 infection, and trimester, as appropriate.Findings: As of Nov 4, 2021, 191 360 women aged 15-49 years with known pregnancy status had completed the first vaccine dose survey and 94 937 had completed the second dose survey. 180 388 received one dose and 94 262 received a second dose of an mRNA vaccine, with 5597 pregnant participants receiving dose one and 3108 receiving dose two, and 174 765 non-pregnant participants receiving dose one and 91 131 receiving dose two. Of 6179 included unvaccinated control participants, 339 were pregnant and 5840 were not pregnant. Overall, 226 (4·0%) of 5597 vaccinated pregnant females reported a significant health event after dose one of an mRNA vaccine, and 227 (7·3%) of 3108 after dose two, compared with 11 (3·2%) of 339 pregnant unvaccinated females. Pregnant vaccinated females had an increased odds of a significant health event within 7 days of the vaccine after dose two of mRNA-1273 (adjusted odds ratio [aOR] 4·4 [95% CI 2·4-8·3]) compared with pregnant unvaccinated controls within the past 7 days, but not after dose one of mRNA-1273 or any dose of BNT162b2. Pregnant vaccinated females had decreased odds of a significant health event compared with non-pregnant vaccinated females after both dose one (aOR 0·63 [95% CI 0·55-0·72]) and dose two (aOR 0·62 [0·54-0·71]) of any mRNA vaccination. There were no significant differences in any analyses when restricted to events which led to medical attention.Interpretation: COVID-19 mRNA vaccines have a good safety profile in pregnancy. These data can be used to appropriately inform pregnant people regarding reactogenicity of COVID-19 vaccines during pregnancy, and should be considered alongside effectiveness and immunogenicity data to make appropriate recommendations about best use of COVID-19 vaccines in pregnancy.Funding: Canadian Institutes of Health Research, Public Health Agency of Canada. [ABSTRACT FROM AUTHOR]

• Survey of clinicians comparing revised product labels to existing labels. • Healthcare providers preferred stakeholder-developed labels over existing labels. • Preference based on clearer wording and relevance to clinical decision-making. • Qualitative responses may help guide additional improvement to labels. • Stakeholder involvement in statement development improved product label information. The World Health Organization recommends immunization with inactivated influenza vaccine (IIV) and tetanus-diphtheria-acellular pertussis (Tdap) vaccine during pregnancy. Yet, product labelling information for IIV and Tdap sends a different message. In a previous study, we developed evidence-based statements about vaccination in pregnancy that could be included in product information. This study compares healthcare providers' perceptions of the revised statements to those currently used in vaccine product labelling information. A 30-item online survey with qualitative and quantitative components was distributed to Canadian maternal healthcare providers via professional organizations and public health. Participants read excerpts from revised and existing IIV and Tdap product labelling information and answered questions about how they perceived the safety and effectiveness of the vaccines, whether they would recommend each vaccine during pregnancy, and which statements they preferred. From June to August 2018, 449 healthcare providers completed the survey, including physicians (45%), nurses (24%), midwives (27%) and others (5%). Most participants perceived the vaccines to be safe and effective based on the revised statements. Over twice as many participants said they would recommend the IIV and Tdap vaccines in pregnancy based on the revised rather than the existing statements (64% versus 21% for IIV and 63% versus 27% for Tdap). Most participants selected that the revised statements better explained the risks and benefits of vaccination in pregnancy (65% versus 21% for IIV; 51% versus 27% for Tdap). Qualitative comments highlighted the strengths of the revised statements and areas for improvement. The majority of participants demonstrated preferences for the revised IIV and Tdap product label statements over the existing statements. Comments suggested the revised statements include improvements to the evidence-base and readability. Involving stakeholders improved the development of product labelling information, but further improvement is needed to support the evidence-based use of vaccines in pregnancy. [ABSTRACT FROM AUTHOR]

• Comparison of vaccine uptake in 2 and 7 year-old children with and without epilepsy. • Vaccine coverage is similar between children with and without epilepsy. • Children diagnosed early have slightly lower vaccine coverage at age 2 years. Children with epilepsy are at increased risk of complications from vaccine-preventable infections, yet information on vaccine coverage in these children is scarce. We aimed to compare vaccine coverage among children with epilepsy to children without epilepsy. We conducted a retrospective cohort study including all 2005–2013 births in Manitoba and Ontario, Canada, creating two cohorts: 2-year-olds and 7-year-olds (followed to age 2 and 7 years). We split each cohort into epilepsy and non-epilepsy subcohorts. We assessed vaccination coverage based on provincial schedules and determined timeliness of MMR (measles, mumps, rubella) dose 1 (recommended at 12 months) and DTaP (diphtheria, tetanus, pertussis) dose 4 (recommended at 18 months). We used logistic regression to calculate adjusted odds ratios (aORs) of the association between epilepsy and vaccination, combining both provincial estimates using random effects meta -analysis. We included 16,558 2-year-olds (Manitoba, 653; Ontario, 15,905) and 13,004 7-year-olds (Manitoba, 483; Ontario, 12,521) with epilepsy. At age 2 years, the aOR for up-to-date vaccination among children with versus without epilepsy was 0.9 (95% confidence interval 0.8–1.1); at age 7 years it was 1.0 (0.9–1.1). Infants diagnosed with epilepsy before age 6 months were less likely to be up-to-date at age 2 years (0.9; 0.8–0.9), although this difference disappeared by age 7 years. Vaccine timeliness was similar between children with and without epilepsy for MMR dose 1 and DTaP dose 4. Overall, this study suggests that children with epilepsy are not significantly under-vaccinated compared to their peers without epilepsy. As children with epilepsy are at a higher risk of complications from vaccine-preventable diseases, vaccination in children with epilepsy should be optimized, especially early in life, as these children may not be able to rely on herd protection. [ABSTRACT FROM AUTHOR]

• We analyzed encephalopathy/encephalitis cases following immunization. • 57 acute and 4 chronic cases were reported via active surveillance over 21 years. • 69% of cases had an alternate cause for encephalopathy/encephalitis than vaccination. • Encephalopathy/encephalitis following vaccination is most often non-vaccine related. Neurological adverse events following immunization (AEFI) remain poorly characterized. Our objective was to describe pediatric acute and chronic encephalopathy and encephalitis cases following immunization reported via active sentinel surveillance from 1992 to 2012. This case series provides a descriptive analysis of encephalopathy/encephalitis admissions reported to the Canadian Immunization Monitoring Program ACTive (IMPACT). Acute cases were reported if symptom onset (seizures, decreased level of consciousness, change in mental status) occurred 0–7 days after tetanus or pertussis-containing vaccines, 0–15 days after other inactivated vaccines, or 5–30 days after live vaccines. Chronic cases of subacute sclerosing panencephalitis or subacute progressive rubella encephalitis were reported at any interval after vaccination. Clinical data were examined to identify possible causes for encephalopathy/encephalitis other than vaccination. Sixty-one cases of encephalopathy/encephalitis following immunization were reported to IMPACT over 21 years; 57 (93.4%) were classified as acute and 4 (6.6%) were chronic cases of subacute sclerosing panencephalitis. Most patients (73.8%) were previously healthy and immunocompetent. The vaccines most frequently administered prior to presentation were diphtheria-tetanus-pertussis, measles-mumps-rubella, and influenza. At discharge, 38 patients (62.3%) had normal neurological status or were expected to recover. Forty patients (70.2%) with acute encephalopathy/encephalitis had a more likely alternate etiology besides vaccination based on neuroimaging, symptoms suggestive of infection, laboratory-confirmed non-vaccine-related infection, or clinical diagnosis. No cases of encephalitis were causally associated with pertussis or influenza vaccines. Two patients (50%) with subacute sclerosing panencephalitis had known wild-type measles infection prior to immunization. Three deaths were reported during hospitalization (4.9%); all were acute encephalitis/encephalopathy cases and none were confirmed to be vaccine-related. Encephalopathy/encephalitis following immunization remains a rare but serious adverse event. Most cases had another more likely etiology than vaccination. Continued monitoring and analysis of AEFI is paramount to ensure the safety of immunization programs. [ABSTRACT FROM AUTHOR]

• Consensus-based methods were used to improve vaccine product label information. • Stakeholders developed structure, language, and content for product labels. • Emergent methods exposed divergent understandings of the purpose of product labels. • Stakeholders were concerned about how product labels are regulated. • Developers of product label information should consider involving end users. Product labelling information describing the use of vaccines in pregnancy continues to contain cautionary language even after clinical and epidemiological evidence of safety becomes available. This language raises safety concerns among healthcare providers who may hesitate to recommend vaccines during pregnancy. To develop clear evidence-based language about vaccine safety and effectiveness in pregnancy for inclusion in vaccine product labels. We conducted a three-stage consensus-methods project with stakeholders, including: healthcare providers, vaccine regulators, industry representatives, and experts in public health, communication, law, ethics, and social sciences. Using qualitative and quantitative methods, we held a nominal group technique (NGT) meeting, followed by a Delphi survey, and then a consensus workshop with a subset of Delphi participants. We developed a methodological tool to analyse data for consensus. Stakeholders (N = 14) at the NGT meeting drafted product label statements for evaluation in the Delphi survey. Survey participants (N = 41) provided feedback on statements for five hypothetical vaccines. Workshop participants (N = 27) initiated discussions that demonstrated a lack of awareness that the regulatory purpose of product labels is to provide a scientific summary of product-specific pre-clinical and clinical trial data. Each stage of this project built on earlier stages until we achieved strong consensus on the language, structure, and types of data that stakeholders wanted to include in inactivated influenza vaccine (IIV) and tetanus-diphtheria-acellular pertussis (Tdap) vaccine product labels in Canada. The revised statements for IIV and Tdap aligned with workshop participants' goals that the product label be evidence-based, with a consistent structure and language that is easily understood by healthcare providers. Emergent methods uncovered stakeholder concerns about the regulatory purpose, content, and evidence used in product labels. Involving healthcare providers in the development and regular updating of product information could prevent interpretations of that information that contribute to vaccine hesitancy. [ABSTRACT FROM AUTHOR]