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Objective: Mathematical models are vital tools to understand transmission dynamics and assess the impact of interventions to mitigate COVID‐19. However, historically, their use in Africa has been limited. In this scoping review, we assess how mathematical models were used to study COVID‐19 vaccination to potentially inform pandemic planning and response in Africa. Methods: We searched six electronic databases: MEDLINE, Embase, Web of Science, Global Health, MathSciNet and Africa‐Wide NiPAD, using keywords to identify articles focused on the use of mathematical modelling studies of COVID‐19 vaccination in Africa that were published as of October 2022. We extracted the details on the country, author affiliation, characteristics of models, policy intent and heterogeneity factors. We assessed quality using 21‐point scale criteria on model characteristics and content of the studies. Results: The literature search yielded 462 articles, of which 32 were included based on the eligibility criteria. Nineteen (59%) studies had a first author affiliated with an African country. Of the 32 included studies, 30 (94%) were compartmental models. By country, most studies were about or included South Africa (n = 12, 37%), followed by Morocco (n = 6, 19%) and Ethiopia (n = 5, 16%). Most studies (n = 19, 59%) assessed the impact of increasing vaccination coverage on COVID‐19 burden. Half (n = 16, 50%) had policy intent: prioritising or selecting interventions, pandemic planning and response, vaccine distribution and optimisation strategies and understanding transmission dynamics of COVID‐19. Fourteen studies (44%) were of medium quality and eight (25%) were of high quality. Conclusions: While decision‐makers could draw vital insights from the evidence generated from mathematical modelling to inform policy, we found that there was limited use of such models exploring vaccination impacts for COVID‐19 in Africa. The disparity can be addressed by scaling up mathematical modelling training, increasing collaborative opportunities between modellers and policymakers, and increasing access to funding. [ABSTRACT FROM AUTHOR]

Summary: Splenectomy/asplenia is a condition associated with immune‐compromission and specific vaccines are recommended for these patients, including the anti‐COVID‐19 vaccine. Among the high‐risk group for which vaccination was prioritized in Italy, the immunocompromised patients after therapies or treatments were included. The Apulian regional archive of hospital discharge forms was used to define the list of splenectomized Apulian inhabitants, considering data from 2015 through 2020. The overall vaccination status of asplenic patients was assessed via data collected from the Regional Immunization Database. The history of SARS‐CoV‐2 infection and the infectious disease outcomes were extracted from the Italian Institute of Health platform "Integrated surveillance of COVID‐19 cases in Italy". 1219 Apulian splenectomized inhabitants were included; the incidence rate of SARS‐CoV‐2 infection was 15.0 per 100 persons‐year with a proportion of re‐infection equal to 6.4%; the proportion of hospitalization was 2.9%, with a case‐fatality rate of 2.6%. The vaccine coverage (VC) for the anti‐COVID‐19 vaccine basal routine was 64.2%, for the first booster dose was 15.4%, and for the second booster dose was 0.6%. A multifactorial approach is needed to increase the vaccination uptake in this sub‐group population and to increase the awareness of the asplenia‐related risks to patients and health personnel. [ABSTRACT FROM AUTHOR]

Several vaccines have been produced in 2 years of the COVID‐19 pandemic to control the infection outbreak. This study demonstrated the success of vaccination in controlling COVID‐19 cases and deaths in a small city (41 424 people) with a low population density in Brazil. This study was based on a 1‐year dataset since the application of the first dose in January 2021. The results show a reduction in positive cases and deaths as the vaccination coverage increased in the city, mainly after 15 000 inhabitants were vaccinated (35.21% of the population) in July 2021. At the time, 49.06% of administered vaccines were ChAdOx1‐S recombinant, 39.80% inactivated SARS‐CoV‐2 virus (CZ02 strain), 9.70% Tozinameran, and 1.44% Ad26.COV2‐S recombinant. From August 2021, a marked reduction in daily positive cases and deaths was observed, and incidence (≤2.49 per 1000 inhabitants) and mortality (≤0.02 per 1000 inhabitants) rates remained stabilized until January 2022, when a new outbreak occurred upon the emergence of the Omicron variant. However, the mortality rate (0.07 per 1000 inhabitants) remained low regardless of the Omicron high incidence rate (68.41 per 1000 inhabitants). These data demonstrate the COVID‐19 vaccination effectiveness with a threshold of 35.21% of the population vaccinated in this city model. [ABSTRACT FROM AUTHOR]

We aim to evaluate the evolution differences in the incidence and case fatality rate (CFR) of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) Delta and Omicron variants. The average incidence and CFRs were described between different countries. A gamma generalized linear mixed model (GLMM) was used to compare the CFRs of Delta and Omicron variants based on vaccination coverage. Totally, 50 countries were included for analyses. The incidence of coronavirus disease 2019 (COVID‐19) ranged from 0.16/100,000 to 82.95/100,000 during the Delta period and 0.03/100,000 to 440.88/100,000 during the Omicron period. The median CFRs were 8.56 (interquartile range [IQR]: 4.76–18.39) during the Delta period and 3.04 (IQR: 1.87–7.48) during the Omicron period, respectively. A total of 47 out of 50 countries showed decreased CFRs of the Omicron variant with the rate ratio ranging from 0.02 (95% confidence interval [CI]: 0.01–0.03) (in Cambodia) to 0.97 (95% CI: 0.87–1.08) (in Ireland). Gamma GLMM analysis showed that the decreased CFR was largely a result of the decreased pathogenicity of Omicron besides the increased vaccination coverage. The Omicron variant shows a higher incidence but a lower CFR around the world as a whole, which is mainly a result of the decreased pathogenicity by SARS‐CoV‐2's mutation, while the vaccination against SARS‐CoV‐2 still acts as a valuable measure in preventing people from death. [ABSTRACT FROM AUTHOR]

Objective: This study aims to examine the factors influencing COVID‐19 vaccine uptake among healthcare professionals (HCPs) and the general population in Cyprus. Methods: A web‐based cross‐sectional study was conducted (November 2021–January 2022), using a self‐administered, anonymous questionnaire to collect information covering a wide range of potential determinants including sociodemographic and health‐related characteristics, trust in the healthcare system, satisfaction with it, utilization of preventive healthcare services, COVID‐19 vaccination information and general vaccination knowledge. Results: A total of 2582 participants completed the survey. Overall, 53.5% of participants representing the general population, and 70.0% of the HCPs received the COVID‐19 vaccination. We found that as the age increases by 1 year among the general population, the odds of being vaccinated against COVID‐19 increase by 1.02 units (95% 1.00, 1.03, p= 0.035). In addition, participants among the general population with increased trust in national healthcare authorities' guidelines (OR = 3.96, 95% CI: 3.41, 4.61), and increased vaccination knowledge scores (OR = 1.11, 95% CI: 1.05, 1.18) were significantly more likely to be vaccinated, while those who had underage children living in the household were significantly less likely to be vaccinated against COVID‐19 (OR = 0.68, 95% CI: 0.50, 0.91). Furthermore, male HCPs (OR = 1.91, 95% CI: 1.01, 3.59), and those who reported increased trust in national healthcare authorities' guidelines (OR = 5.38, 95% CI: 3.65, 7.95) were significantly more likely to be vaccinated. Conclusion: Public health policymakers can use national campaigns and long‐term planning to build public trust in national healthcare authorities and raise awareness about the benefits of vaccination. Such strategies could pave the way for adequate vaccine uptake and prepare the public for unfavourable scenarios, such as future pandemics. [ABSTRACT FROM AUTHOR]

To mitigate SARS‐CoV‐2 transmission, vaccines have been urgently approved. With their limited availability, it is critical to distribute the vaccines reasonably. We simulated the SARS‐CoV‐2 transmission for 365 days over four intervention periods: free transmission, structural mitigation, personal mitigation, and vaccination. Sensitivity analyses were performed to obtain robust results. We further evaluated two proposed vaccination allocations, including one‐dose‐high‐coverage and two‐doses‐low‐coverage, when the supply was low. 33.35% (infection rate, 2.68 in 10 million people) and 40.54% (2.36) of confirmed cases could be avoided as the nonpharmaceutical interventions (NPIs) adherence rate rose from 50% to 70%. As the vaccination coverage reached 60% and 80%, the total infections could be reduced by 32.72% and 41.19%, compared to the number without vaccination. When the durations of immunity were 90 and 120 days, the infection rates were 2.67 and 2.38. As the asymptomatic infection rate rose from 30% to 50%, the infection rate increased 0.92 (SD, 0.16) times. Conditioned on 70% adherence rate, with the same amount of limited available vaccines, the 20% and 40% vaccination coverage of one‐dose‐high‐coverage, the infection rates were 2.70 and 2.35; corresponding to the two‐doses‐low‐coverage with 10% and 20% vaccination coverage, the infection rates were 3.22 and 2.92. Our results indicated as the duration of immunity prolonged, the second wave of SARS‐CoV‐2 would be delayed and the scale would be declined. On average, the total infections in two‐doses‐low‐coverage was 1.48 times (SD, 0.24) as high as that in one‐dose‐high‐coverage. It is crucial to encourage people in order to improve vaccination coverage and establish immune barriers. Particularly when the supply is limited, a wiser strategy to prevent SARS‐CoV‐2 is equally distributing doses to the same number of individuals. Besides vaccination, NPIs are equally critical to the prevention of widespread of SARS‐CoV‐2. [ABSTRACT FROM AUTHOR]

Background: Individuals in contact with persons with COVID‐19 are at high risk of developing COVID‐19; protection offered by COVID‐19 vaccines in the context of known exposure is poorly understood. Methods: Symptomatic outpatients aged ≥12 years reporting acute onset of COVID‐19‐like illness and tested for SARS‐CoV‐2 between February 1 and September 30, 2021 were enrolled. Participants were stratified by self‐report of having known contact with a COVID‐19 case in the 14 days prior to illness onset. Vaccine effectiveness was evaluated using the test‐negative study design and multivariable logistic regression. Results: Among 2229 participants, 283/451 (63%) of those reporting contact and 331/1778 (19%) without known contact tested SARS‐CoV‐2‐positive. Adjusted vaccine effectiveness was 71% (95% confidence interval [CI], 49%–83%) among fully vaccinated participants reporting a known contact versus 80% (95% CI, 72%–86%) among those with no known contact (p‐value for interaction = 0.2). Conclusions: This study contributes to growing evidence of the benefits of vaccinations in preventing COVID‐19 and support vaccination recommendations and the importance of efforts to increase vaccination coverage. [ABSTRACT FROM AUTHOR]

Objective: To estimate the numbers of COVID‐19‐related hospitalisations in Australia after re‐opening the international border. Design: Population‐level deterministic compartmental epidemic modelling of eight scenarios applying various assumptions regarding SARS‐CoV‐2 transmissibility (baseline R0 = 3.5 or 7.0), vaccine rollout speed (slow or fast), and scale of border re‐opening (mean of 2500 or 13 000 overseas arrivals per day). Setting: Simulation population size, age structure, and age‐based contact rates based on recent estimates for the Australian population. We assumed that 80% vaccination coverage of people aged 16 years or more was reached in mid‐October 2021 (fast rollout) or early January 2022 (slow rollout). Main outcome measures: Numbers of people admitted to hospital with COVID‐19, December 2021 ‒ December 2022. Results: In scenarios assuming a highly transmissible SARS‐CoV‐2 variant (R0 = 7.0), opening the international border on either scale was followed by surges in both infections and hospitalisations that would require public health measures beyond mask wearing and social distancing to avoid overwhelming the health system. Reducing the number of hospitalisations to manageable levels required several cycles of additional social and mobility restrictions. Conclusions: If highly transmissible SARS‐CoV‐2 variants are circulating locally or overseas, large and disruptive COVID‐19 outbreaks will still be possible in Australia after 80% of people aged 16 years or more have been vaccinated. Continuing public health measures to restrict the spread of disease are likely to be necessary throughout 2022. [ABSTRACT FROM AUTHOR]

Two conundrums puzzle COVID‐19 investigators: 1) morbidity and mortality is rare among infants and young children and 2) rates of morbidity and mortality exhibit large variances across nations, locales, and even within cities. It is found that the higher the rate of pneumococcal vaccination in a nation (or city) the lower the COVID‐19 morbidity and mortality. Vaccination rates with Bacillus Calmette–Guerin, poliovirus, and other vaccines do not correlate with COVID‐19 risks, nor do COVID‐19 case or death rates correlate with number of people in the population with diabetes, obesity, or adults over 65. Infant protection may be due to maternal antibodies and antiviral proteins in milk such as lactoferrin that are known to protect against coronavirus infections. Subsequent protection might then be conferred (and correlate with) rates of Haemophilus influenzae type B (Hib) (universal in infants) and pneumococcal vaccination, the latter varying widely by geography among infants, at‐risk adults, and the elderly. Also see the video abstract here https://youtu.be/GODBYRbPL00. [ABSTRACT FROM AUTHOR]

Whether COVID‐19‐related morbidity and mortality are increased in splenectomized patients is unknown. The study by Bianchi et al. suggests increased hospitalizations and mortality rates in splenectomized patients, despite observing similar infection rates when compared to the general population. Commentary on: Bianchi et al. Burden of COVID19 disease and vaccine coverages in Apulian splenectomized patients. A retrospective observational study. Br J Haematol 2023;201:1072–1080. [ABSTRACT FROM AUTHOR]