Events supposedly attributable to vaccination or immunization of COVID-19 vaccines in Brazil: a cross-sectional study

COVID-19 vaccines effectively reduce morbidity and mortality but are associated with Events Supposedly Attributable to Vaccination or Immunization (ESAVI). This cross-sectional study examined the incidence and characteristics of ESAVI in Brazil during 2021, using data from e-SUS Notifica and Vacivida. Among 109,424 reports, the incidence rates were 30.82 ESAVI and 83.08 symptoms per 100,000 doses. Most reports involved women (70.83%), individuals aged 30-39, and residents of the southern region. Common symptoms included headache, fever, and myalgia. AstraZeneca accounted for 56.79% of cases. Non-severe cases predominated (95.03%), with 78.7% classified as "product-related according to the literature." Mortality was rare (0.03%), but a significant association was identified between DNA vaccines and deaths (chi 2 = 4.333; p = 0.037; OR = 2.673; 95% CI 1.020-7.007). Regional disparities were evident, with higher incidences in the South and Southeast. Underreporting of non-severe cases remains a challenge. Logistic regression showed lower odds of severe ESAVI among adults and Black/Brown individuals, while Pfizer vaccines and initial doses were linked to higher odds. These results highlight the safety of COVID-19 vaccines in Brazil while emphasizing the need for strengthened post-vaccination surveillance to address regional disparities, health inequities, and vaccine hesitancy.