ABSTRACT
ObjectiveIn Japan, healthcare workers (HCWs) are vaccinated against contagious viruses (measles, rubella, chickenpox, mumps, and hepatitis B) to prevent nosocomial infection; however, some do not produce sufficient antibodies (suboptimal responders). Whether suboptimal responders to live attenuated viruses or inactivated viruses vaccines can produce adequate antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines remains to be elucidated. MethodsIn this prospective cohort study, SARS-CoV-2 anti-spike antibodies were measured 11 times, from before the first BNT162b2 vaccination to 5 months after the second vaccination. Antibody titers of suboptimal and normal responders were compared. SARS-CoV-2 neutralizing antibody activity was measured twice in suboptimal responders, 1 week to 1 month, and 5 months after the second vaccination. PatientsThis study included 50 HCWs who received two doses of mRNA BNT162b2 vaccine 3 weeks apart. ResultsAfter vaccination, the SARS-CoV-2 anti-spike antibody was detectable in the samples from suboptimal and normal responders at each timepoint. The median SARS-CoV-2 anti-spike antibody titer was higher in suboptimal responders than in normal responders 1 week after receiving the second dose of BNT162b2 vaccine (3721.0 vs. 2251.5, P=0.029). Suboptimal responders had SARS-CoV-2 neutralizing antibody activity 1 week to 1 month, and 5 months after the second vaccination, which exceeded the positive threshold 5 months after the second vaccination. ConclusionAfter BNT162b2 vaccination, suboptimal responders acquired adequate SARS-CoV-2 anti-spike and SARS-CoV-2 neutralizing antibodies to prevent SARS-CoV-2. These results suggest that vaccination with mRNA vaccine against SARS-CoV-2 should also be recommended for suboptimal responders to conventional vaccines.
