Headache as the most prevalent post-vaccination adverse event after Covid-19 vaccination

BACKGROUND: In 2020, the first vaccines were approved, according to the WHO. However, speculations arose regarding their efficacy and post-vaccination adverse events (AEFV). OBJECTIVE: To evaluate the prevalence of headache as AEFI from the SARSCoV-2 vaccine in Piauí, Brazil. METHODS: This is a quantitative, observational, cross-sectional, and prevalence study. Data were provided by the Post-Vaccination Adverse Event Information System (SI-AEFV), from reported cases from January to September 2021. Data were analyzed, and the research was approved by the UFPI Research Ethics Committee. RESULTS: A total of 2,008 cases were analyzed. Headache was reported in 752 cases (27.99%) as an AEFV after vaccination against SARS-CoV-2. In most cases, patients were from Teresina (67.62%), of brown race/ethnicity (52.67%), female (79.00%), and the majority were not healthcare professionals (54.27%). The most common age of patients, with the original data, was 33 years. After data correction, the most common age was 28 years. The majority of these cases were not severe (96.44%), and the majority of cases were associated with the first dose of the Covid-19-Covishield-Oxford/AstraZeneca vaccine (43.18%).CONCLUSION: Thus, it is concluded from the partial analysis of the results that headache is the most common adverse event after vaccination against SARS-CoV-2. The profile of patients with the most notifications was brown women aged 30 to 40 years who received the first dose of the Covid-19-Covishield-Oxford/AstraZeneca vaccine. Regarding the severity of events, the vast majority were considered non-severe, and no deaths were mentioned, demonstrating the safety of immunobiologicals.