The following is the summary of “Association between IgG antibody levels and adverse events after first and second Bnt162b2 mRNA vaccine doses” published in the December 2022 issue of Clinical microbiology and infections by Braun, et al.

This research aimed to find a link between the amount of IgG antibodies produced in response to the BNT162b2 (Pfizer BioNTech) mRNA vaccine against SARS-CoV-2 after the first and second doses and the occurrence of adverse events. Participants in this cohort research were BNT162b2 vaccine recipients at their institution between October 2020 and May 2021. An electronic questionnaire was used to collect data on adverse events, age, and sex, and SARS-CoV-2 IgG antibody levels were obtained from the hospital’s electronic medical record system.

A total of 9,700 first-dose vaccination recipients and 8,321 second-dose vaccine recipients filled out the adverse events questionnaire between December 2020 and May 2021. Antibody levels were, on average, 62.34 AU/mL (mean 4,373) after the first dose and 188.19 AU/mL (mean 20392) after the second. Except for localized pain, the incidence of all other side effects increased following the second vaccination. In addition, after the initial vaccination, a higher incidence of adverse events was linked to female sex and younger age (but not IgG titers; OR 2.377, 95% CI, 1.607-3.515, P=0.000; OR 0.959, 95% CI, 0.944-0.977, p£0.000; OR 1.002, 95% CI, 0.995-1.008, P £0.601; respectively).

However, all 3 parameters were linked to the incidence of adverse events after the second dose (OR 2.332, 95% CI, 1.636–3.322, P=0.000; OR 0.984, 95% CI, 0.970–0.999, P£0.039; OR 1.004, 95% CI, 1.001–1.007, P £0.022; respectively). The incidence of adverse events increases significantly after a second dosage of the BNT162b2 vaccination compared to the incidence after the first dose. The incidence of adverse events was correlated with sex, age, and SARS-CoV-2 IgG antibody titer.