PMID- 35643563 OWN - NLM STAT- MEDLINE DCOM- 20220615 LR - 20221221 IS - 1873-2518 (Electronic) IS - 0264-410X (Print) IS - 0264-410X (Linking) VI - 40 IP - 28 DP - 2022 Jun 21 TI - Safety of Pfizer-BioNTech vaccine in a cohort of healthcare providers: Differences between naive and previously infected by SARS-CoV-2. PG - 3818-3820 LID - S0264-410X(22)00586-2 [pii] LID - 10.1016/j.vaccine.2022.05.015 [doi] AB - INTRODUCTION: The Spanish Society of Immunology recently warned that a history of past COVID-19 could result in a higher incidence of adverse events (AEs) related to vaccination. We set out to analyze whether there were any differences in AEs between healthcare workers vaccinated for COVID-19 (either after the first or second dose) who had had a prior diagnosis SARS-CoV-2 infection at any time compared to those who had not had COVID-19 before vaccination. METHODS: This was a retrospective cohort study in a population of healthcare workers. AEs related to the first and second doses of the Pfizer vaccine were recorded. We compared the incidence of AEs and compared individuals with 0-3 different AEs to those with 4 or more AEs. The relative risks (RR) and their 95% confidence intervals were calculated. RESULTS: Past infection was associated with having more AEs after the first dose (p < 0.001), but not the second one (p = 0.476), as well as a higher incidence of AEs (p < 0.001). Common AEs that were statistically associated with past COVID infection included arthralgia, asthenia, fever, chills, headache, and myalgia (p