Effectiveness of the severe acute respiratory syndrome coronavirus 2 Omicron BA.5 bivalent vaccine on symptoms in healthcare workers with BA.5 infection.

Background: The infection status of healthcare workers (HCWs) with coronavirus disease 2019 has become a major concern worldwide. In this study, we investigated the efficacy of the number of vaccine doses on symptoms after BA.5-adapted bivalent vaccination in HCWs.

Antibody Response to the BA.5 Bivalent Vaccine Shot: a Two-Year Follow-Up Study following Initial COVID-19 mRNA Vaccination.

Although many studies have been conducted on the increase in spike antibody levels after vaccination, there is insufficient prospective and longitudinal information on the BA.5-adapted bivalent vaccine up to the fifth vaccination. In this study, we conducted a follow-up study of spike antibody levels and infection history in 46 health care workers who received up to 5 vaccinations.

Robust Antibody Responses to the BNT162b2 mRNA Vaccine Occur Within a Week After the First Dose in Previously Infected Individuals and After the Second Dose in Uninfected Individuals.

Background: Vaccines against severe acute respiratory syndrome coronavirus 2 can trigger acquired immunity in infection-naïve individuals and offer a path toward ending the coronavirus disease pandemic that began in 2019. However, the kinetics of early antibody responses in vaccinated individuals remain poorly understood.

Method: We followed BNT162b2 mRNA-vaccinated health care workers (HCWs, N=108) including 103 infection-naïve and five previously infected individuals.