key: cord-0766320-qht8ckxu authors: Chandan, Saurabh; Khan, Shahab R.; Deliwala, Smit; Mohan, Babu P.; Ramai, Daryl; Chandan, Ojasvini C.; Facciorusso, Antonio title: Postvaccination SARS‐CoV‐2 infection among healthcare workers: A systematic review and meta‐analysis date: 2021-11-24 journal: J Med Virol DOI: 10.1002/jmv.27457 sha: 6c65f4acc3e4b2c883ea2bd6b7100393a86f74a9 doc_id: 766320 cord_uid: qht8ckxu Healthcare workers (HCWs) remain on the front line of the battle against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) and coronavirus disease 2019 (COVID‐19) infection and are among the highest groups at risk of infection during this raging pandemic. We conducted a systematic review and meta‐analysis to assess the incidence of postvaccination SARS‐CoV‐2 infection among vaccinated HCWs. We searched multiple databases from inception through August 2021 to identify studies that reported on the incidence of postvaccination SARS‐CoV‐2 infection among HCWs. Meta‐analysis was performed to determine pooled proportions of COVID‐19 infection in partially/fully vaccinated as well as unvaccinated individuals. Eighteen studies with 228 873 HCWs were included in the final analysis. The total number of partially vaccinated, fully vaccinated, and unvaccinated HCWs were 132 922, 155 673, and 17 505, respectively. Overall pooled proportion of COVID‐19 infections among partially/fully vaccinated and unvaccinated HCWs was 2.1% (95% confidence interval [CI] 1.2–3.5). Among partially vaccinated, fully vaccinated and unvaccinated HCWs, pooled proportion of COVID‐19 infections was 2.3% (CI 1.2–4.4), 1.3% (95% CI 0.6–2.9), and 10.1% (95% CI 4.5–19.5), respectively. Our analysis shows the risk of COVID‐19 infection in both partially and fully vaccinated HCWs remains exceedingly low when compared to unvaccinated individuals. There remains an urgent need for all frontline HCWs to be vaccinated against SARS‐CoV‐2 infection. Recent data suggest that these vaccines are highly effective under real-world conditions in preventing symptomatic COVID-19 in HCWs, including those at risk for severe COVID-19. [3] [4] [5] Despite the global push for vaccination, studies show that vaccine hesitancy among HCWs is still common with acceptance rates ranging widely from 27.7% to 77.3%. Demographic variables such as men, older age, and physicians were positive predictive factors, whereas concerns for safety, efficacy and effectiveness, and distrust of the government were barriers. 6 In recent months, there have been further concerns about the emergence of SARS-CoV-2 variants, including variants first reported convert the text to English. An example search strategy using EMBASE is presented as Appendix-S1. Articles were included if data with regard to incidence of postvaccination COVID-19 infection was presented. Only cohort studies were eligible for inclusion. All other study designs including, case series of less than 10 patients, case reports, review articles, and guidelines were excluded. As the included studies were observational in design, the MOOSE (Meta-analyses Of Observational Studies in Epidemiology) Checklist was followed 9 and is provided as Appendix-S2. PRISMA Flowchart for study selection 10 is provided as Appendix-S3. Reference lists of evaluated studies were further examined to identify other studies of interest. Data on study-related outcomes from the individual studies were abstracted independently onto a standardized form by at least two authors (SC and SRK). Authors (DR and OCC) cross-verified the collected data for possible errors and two authors (SC and SRK) performed the quality scoring independently. We used the Newcastle-Ottawa scale, which is a quality score consisting of 8 questions, to assess the quality of cohort studies. 11 We used meta-analysis techniques to calculate the pooled estimates in each case following the methods suggested by DerSimonian and Laird using the random-effects model and results were expressed in terms of pooled proportion (PP) along with relevant 95% confidence intervals (CIs). 12 When the incidence of an outcome was zero in a study, a continuity correction of 0.5 was added to the number of incident cases before statistical analysis. 13 A p-value of < 0.05 was defined as statistically significant. We assessed heterogeneity between study-specific estimates by using Cochran Q statistical test for heterogeneity, 95% confidence interval (CI), and the I 2 statistics. [13] [14] [15] In this, values of <30%, 30%-60%, 61%-75%, and >75% were suggestive of low, moderate, substantial, and considerable heterogeneity, respectively. We assessed publication bias, qualitatively, by visual inspection of funnel plot and quantitatively, by the Egger test. 16 When publication bias was present, further statistics using the fail-Safe N test and Duval and Tweedie's "Trim and Fill" test were used to ascertain the impact of the bias. 17 All analyses were performed using Comprehensive Meta-Analysis (CMA) software, version 3 (BioStat). Six studies originated from India, [18] [19] [20] [21] [22] [23] seven from the USA, 1, [24] [25] [26] [27] [28] [29] two from Israel, 30, 31 and one each from Pakistan, 32 United Kingdom, 33 and Indonesia. 34 Further details of patient characteristics, category of healthcare workers, follow-up time and type of infection, symptomatic, or asymptomatic are presented in Tables 1 and 2. Ten of the included studies were retrospective in design while four were prospective. Based on the New-Castle Ottawa scoring system, all included studies were considered to be of high quality. To assess whether any one study had a dominant effect on the metaanalysis, we excluded one study at a time and analyzed its effect on the main summary estimate. We found that exclusion of any single study did not significantly affect the primary outcome or influence the heterogeneity. We assessed the dispersion of the calculated rates using the I 2 percentage values as reported in the meta-analysis outcomes section. We found considerable heterogeneity in our outcomes. This is likely due to variations in the sample size of each individual study, the type of COVID-19 vaccine administered, and variation in mean follow-up time. Based on visual inspection of the funnel plot for our study outcomes, we found no evidence of publication bias. Quantitative assessment demon- Our analysis shows the risk of COVID-19 infection in both partially and fully vaccinated HCWs remains exceedingly low when compared to unvaccinated individuals. We found that while the pooled proportion of unvaccinated HCWs contracting COVID-19 was as high as 47%, this decreased to 2.3% for partially vaccinated and 1.3% for fully vaccinated HCWs. At the time of writing, the COVID-19 pandemic continues to rage across the world and HCWs account for a large number of infected people. 35 These individuals are both not only victims of the disease, but also potential spreaders. 36 Therefore, protecting HCWs from SARS-CoV-2 infection would not only be beneficial for themselves, but also for their household contacts and patients. Vaccine acceptance among HCWs and hesitancy remains a concern with studies showing that nurses and assistant nurses were less prone to accept vaccination against COVID-19 than physicians. 37 Our study is crucial in that it is the first in the literature to systematically review and analyze the incidence of COVID-19 infections among partially/fully vaccinated or unvaccinated HCWs. In December 2020, two messenger RNA (mRNA) vaccines, the should be considered to increase COVID-19 vaccination uptake in these high-risk individuals. 43 Studies have also shown that vaccination amongst health care workers is associated with a substantial reduction in COVID-19 cases in household contacts consistent with an effect of vaccination on transmission. 44 At the peak of the pandemic, assessing published data between May 1 and July 9, 2020, researchers found that a significant number of HCW were reported to be infected with COVID-19 during the first 6 months of the COVID-19 pandemic, with a prevalence of hospitalization of 15.1% and mortality of 1.5%. 45 With that in mind, The authors declare that there are no conflict of interests. The data that support the findings of this study are available from the corresponding author upon reasonable request. 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