Introduction:
The 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 methods:
578 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.

Results:
The 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).

Conclusions:
The 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.