Relationship between degree of adverse reactions and amount of antibody in healthy subjects after the second BNT162b2 vaccination

Abstract

Adverse reactions such as fever, headache, and fatigue after vaccination are one of the major anxiety factors for the general public in preventing the spread of Covid-19 infection. The subjects were 269 staff members (M:F = 60%:40%) who received the second dose of Pfizer’s mRNA vaccine at our hospital. The association of adverse reactions with the IgG antibody titer for the binding domain was examined considering factors such as age and gender. The median sIgG antibody titer was 1,299.5 AU/mL (800.2 AU/mL to 1,947.3 AU/mL), and all the subjects were antibody-positive (50 AU/mL or higher), with an extensive range. There was no significant difference between men and women. When the subjects were divided into four age groups from the 20s to 50s and the antibody titers were compared, a statistically significant difference was observed among the age groups. Drinking habits and taking anti-allergic drugs did not affect the sIgG antibody titers. The criteria for “with adverse reactions” in this study were having a fever of 37.5°C or higher, and one or more systemic symptoms of headache, malaise, and arthralgia whose severity was “disturbing life”. Overall, males and females in the group with adverse reactions all tended to have significantly higher sIgG antibody titers. Any systemic symptoms other than fever as an adverse reaction could be a predictive factor for the acquisition of neutralizing antibodies.