Key result
Prior SARS-CoV-2 infection in vaccinated healthcare workers was associated with higher median anti-S IgG titers (1899.89 vs 1807.30 BAU/mL) compared to uninfected workers.
Why the study?
The study aimed to assess antibody responses to SARS-CoV-2 mRNA vaccines among healthcare workers in Japanese outpatient clinics, examining the effects of baseline characteristics and prior infections.
Does prior SARS-CoV-2 infection and mRNA vaccination increase anti-S and anti-N IgG titers in healthcare workers?
Cohort (n=101)
Yes
Does prior SARS-CoV-2 infection and mRNA vaccination increase anti-S and anti-N IgG titers in healthcare workers?
Effect estimate: 1.1 to 5.8 times higher
Absolute Event Rate: 1899.89% vs 1807.3%
Infection and mRNA vaccination significantly increase anti-S and anti-N IgG titers in healthcare workers, though the impact of hybrid immunity varies by sampling timing.
BACKGROUND: This study aimed to assess the antibody response to SARS-CoV-2 vaccines among healthcare workers (HCWs) from multiple outpatient clinics in Japan, examining the effects of baseline characteristics (e.g., sex, age, underlying condition, smoking history, occupation) and prior infections. METHODS: A total of 101 HCWs provided serum at four time points between October 2020 and July 2023. HCWs received two to six doses of mRNA vaccine (BNT162b2 or mRNA-1273). Anti-nucleocapsid (N) and anti-spike (S) IgG antibodies against the ancestral Wuhan strain were measured using the Abbott Architect™ SARS-CoV-2 IgG assay. Univariate and regression analysis evaluated factors such as past infections, age, sex, smoking, underlying condition, and occupation. RESULTS: After four to six doses, the median anti-S IgG titer in uninfected HCWs was 1807.30 BAU/mL, compared to 1899.89 BAU/mL in HCWs with prior infections. The median anti-N IgG titer was 0.10 index S/C in uninfected HCWs and 0.39 index S/C in infected HCWs. HCWs with prior infection had anti-S IgG titers 1.1 to 5.8 times higher than those without. Univariate and multivariate analyses indicated infection and vaccination significantly increased anti-S and anti-N IgG titers. Age, sex, smoking history and occupation did not influence antibody titers while underlying conditions were associated with lower anti-N IgG titers. CONCLUSIONS: Infection and vaccination were strongly associated with an increase in anti-S and anti-N IgG titers; however, the impact of hybrid immunity appeared to be limited and varied depending on the timing of the sampling. These findings provide valuable insights for developing personalized vaccination strategies and future vaccine development.
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Otoguro et al. (2025) conducted a cohort in SARS-CoV-2 vaccination (n=101). Prior SARS-CoV-2 infection vs. No prior SARS-CoV-2 infection was evaluated on Median anti-spike (S) IgG titer after four to six vaccine doses (BAU/mL) (1.1 to 5.8 times higher). Prior SARS-CoV-2 infection in vaccinated healthcare workers was associated with higher median anti-S IgG titers (1899.89 vs 1807.30 BAU/mL) compared to uninfected workers.
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