Debes AK, Xiao S, Colantuoni E, et al. - Hospital workers (HWs) who received the Moderna vaccine, had prior SARS-CoV-2 infection, and experienced clinically significant reactions had higher spike IgG antibody measurements. However, uncertainty remains concerning the role of higher antibody levels in preventing COVID-19 and providing lasting immunity.

• A total of 954 HWs completed a questionnaire and provided serum samples 14 or more days following dose 2.

• Clinically significant symptoms were reported by 52 of the 954 (5%) and 407 (43%) after dose 1 and 2, respectively.

• A strong antibody response to the spike protein appeared in nearly 100% of HWs after dose 2 of the SARS-CoV-2 mRNA vaccine; this appeared independent of vaccine-induced reactions.