Does prior SARS-CoV-2 infection increase the risk of adverse effects after mRNA vaccination (BNT162b2) - the retrospective cohort study of physicians.

IntroductionThe COVID-19 pandemic has caused major changes in society. The prolonged lockdown led to economic collapse in many countries. Because of this reason, vaccination against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the only hope that may reduce spread of the virus. This study aimed to assess the relationship between the severity of adverse effects after COVID-19 vaccine and prior SARS-CoV-2 infection.Material and methods578 physicians vaccinated with two doses of BNT162b2 were included in the study. Via a form on the Google Form platform data about past SARS-CoV-2 infection and observed adverse effects after taking the vaccination were collected.ResultsThe most common adverse effects were local symptoms (pain at the injection site, limitation of mobility of the upper limb). Pain at injection site occurred in 96,2% of cases after first dose of vaccination. Systemic symptoms (weakness, myalgia, fever) appeared less frequently however after second dose occurred statistically significantly more often than after the first one (χ2 = 121.99,p < 0.001). Statistically, symptoms appeared more often after the first dose in the group of doctors with previous SARS-CoV-2 infection (χ2 = 10.85,p = 0.001). Moreover, in this group, the severity of symptoms after first dose was greater (p< 0.001). However, an inverse relationship was observed after second dose of the vaccination (p< 0.001).ConclusionsThe severity of symptoms after the first dose of the vaccine is greater in people who had been infected with SARS-CoV-2 in the past than people not suffering from COVID-19, but after second dose this relationship is reversed.