Effect of COVID-19 vaccination on viral clearance and antibody production in older patients with SARS-CoV-2 infection

Whether coronavirus disease 2019 (COVID-19) vaccination promotes viral clearance in older patients has not been reported. We performed a retrospective review of patients hospitalized with COVID-19. This study included 24 patients with COVID-19 admitted to Hiroshima City Funairi Citizens Hospital between June 1 and July 10, 2021. Nine patients who were vaccinated (median age: 72 years) were compared with 15 patients who were not vaccinated (median age: 70 years). Viral clearance was confirmed by SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR). Antibody titers were measured to assess vaccination efficacy. The vaccinated group had a higher negative conversion rate than that in the non-vaccinated group on RT-PCR testing before discharge (83% vs. 36%, P = 0.064). Antibody titers on admission and 10 ± 2 days after onset were significantly higher in the vaccinated group than those in the non-vaccinated group (35 vs. 0 binding antibody units (BAU)/mL, P = 0.012; and 114 vs. 7 BAU/mL, P = 0.032, respectively). Stimulating antibody production by vaccination may promote faster viral clearance in older patients who develop COVID-19.