ArticleRevista da Sociedade Brasileira de Medicina Tropical2026
Prolonged Evaluation of COVID-19 Vaccine Effectiveness in Healthcare Workers at a Public Tertiary Hospital: A Retrospective Cohort Study.
Article in Revista da Sociedade Brasileira de Medicina Tropical, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
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12 authors.
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Abstract
backgroundMost studies evaluating COVID-19 vaccine efficacy and effectiveness were conducted over short follow-up periods due to the urgency of vaccine approval and rollout during the pandemic. This study aimed to assess the long-term effectiveness of COVID-19 vaccines among healthcare workers at a tertiary hospital.
methodsWe conducted an open retrospective cohort study at Hospital das Clínicas de Ribeirão Preto, including healthcare workers employed between July 3, 2020, and February 8, 2022. A total of 7,385 workers were followed for 3,185,239 person-days. Three monovalent vaccines were administered during the study period: Coronavac™ (Sinovac), Covishield™ (AstraZeneca), and Comirnaty™ (Pfizer-BioNTech). Participants were categorized as unvaccinated, partially vaccinated, or fully vaccinated. The unadjusted relative risk (RR) of COVID-19 was calculated for vaccinated groups compared with the unvaccinated group.
resultsFor COVID-19 of any severity, the RR was 0.72 (95%CI: 0.59-0.89) among partially vaccinated and 1.30 (95%CI: 1.19-1.44) among fully vaccinated workers. For severe or critical cases, the RR was 0.75 (95%CI: 0.26-2.16) with partial vaccination and 0.14 (95%CI: 0.05-0.41) with full vaccination. For COVID-19-related deaths, the RR with full vaccination was 0.32 (95%CI: 0.03-3.09).
conclusionsThe vaccines provided limited long-term protection against SARS-CoV-2 infection and mild COVID-19. However, protection against severe disease and death remained substantial despite the circulation of multiple variants.
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