Safety profile of viral vector vaccines in Brazil: A systematic review of events supposedly attributable to vaccination or immunization (ESAVI)
DOI:
https://doi.org/10.5281/zenodo.21544053Keywords:
adverse effects, drug-related side effects and adverse reactions, viral vector vaccines, pharmacovigilance, COVID-19, Brazil, systematic reviewAbstract
Background: Events supposedly attributable to vaccination or immunization (ESAVI) associated with viral vector vaccines represent a critical challenge for epidemiological surveillance. The introduction of adenovirus-based platforms against COVID-19 required rigorous monitoring to maintain public confidence and characterize safety profiles in “real-world” settings.
Objective: To identify and analyze the most frequently reported ESAVI associated with viral vector vaccines used in Brazil, in order to characterize the epidemiological profile and guide evidence-based immunization policies.
Methods: A systematic review was conducted following the PRISMA 2020 guidelines in PubMed, SciELO, LILACS and national surveillance systems (eSUS Notifica, VigiMed). Studies published between 2020 and 2025 reporting clinical and epidemiological analyses of ESAVI for viral vector vaccines (ChAdOx1 and Ad26.COV2.S) in the Brazilian population were included. Risk of bias was assessed using Joanna Briggs Institute (JBI) tools and the Newcastle–Ottawa Scale (NOS).
Results: Eight studies were included from a total of 181 records identified. Reported incidence ranged from 30.8 to 32.7 ESAVI per 10,000–100,000 doses. The ChAdOx1 vaccine (AstraZeneca) accounted for approximately 56.8% of reported cases, showing greater reactogenicity compared with other platforms. The most consistent finding was the predominance of nonserious, transient and self-limited adverse events (headache, myalgia and local pain), without identification of new unexpected safety signals.
Conclusions: Viral vector vaccines in Brazil have a favorable safety profile, characterized by predominantly nonserious events. National pharmacovigilance systems demonstrated capacity to capture and analyze ESAVI in a timely manner, reinforcing that the benefit–risk balance of these platforms remains positive.
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Copyright (c) 2026 Mariana Goulart de Oliveira, Fernanda Guin de Souza Torejani, Guilherme M. Pedrosa, Juliana Cardozo Silva, Pedro Henrique Da Silva Ardenghi, Talles De Souza Pinto, Lucas Henrique Gimenes , Andrea Paola Britos Gómez (Autor/a)
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