RESUMEN
Background: We aimed to examine the association among nucleocapsid (N) antibodies, a combination of N and spike (S) antibodies, and protection against SARS-CoV-2 reinfection. Methods: We conducted a prospective cohort study among staff at a national medical research center in Tokyo and followed them for the incidence of SARS-CoV-2 infection between June and September 2023 (Omicron XBB.1.16/EG.5 wave). At baseline, participants donated blood samples to measure N- and S-specific antibodies. Cox regression was used to estimate the hazard ratio and protection ([1 - hazard ratio] × 100) against subsequent SARS-CoV-2 infection across these antibody levels. Results: Among participants with previous infection, higher pre-reinfection N antibodies were associated with a lower risk of reinfection, even after adjusting S antibody levels (P < .01 for trend). Estimation of the protection matrix for N and S antibodies revealed that high levels in N and S antibodies conferred robust protection (>90%) against subsequent infection. In addition, a pattern of low pre-reinfection N antibodies but high vaccine-enhanced S antibodies showed high protection (>80%). Conclusions: Pre-reinfection N antibody levels correlated with protection against reinfection, independent of S antibodies. If the N antibodies were low, vaccine-boosted S antibodies might enhance the reinfection protection.
RESUMEN
BACKGROUND & AIMS: Vitamin D deficiency is a common nutritional problem worldwide that may have worsened during the coronavirus disease 2019 (COVID-19) pandemic. The present study sought to examine the prevalence and correlates of vitamin D deficiency among healthcare workers three years after the start of the COVID-19 pandemic. METHODS: Participants comprised 2543 staff members from a medical research institute, who completed a questionnaire and donated blood samples in June 2023. 25-hydroxyvitamin D (25[OH]D) levels were measured using an electrochemiluminescence immunoassay. Logistic regression was used to calculate the odds ratio and its 95% confidence interval while adjusting for covariates. RESULTS: The proportions of participants with vitamin D insufficiency (25[OH]D 20-29 ng/mL) and deficiency (25[OH]D < 20 ng/mL) were 44.9% and 45.9%, respectively. In a multivariable-adjusted model, factors associated with a higher prevalence of vitamin D deficiency included younger age, female sex, fewer hours of daytime outdoor physical activity during leisure time (without regular use of sunscreen), lower intake of fatty fish, no use of vitamin D supplements, smoking, and no alcohol consumption. Occupational factors, including shift work, were not independently associated with vitamin D deficiency. CONCLUSIONS: Our results suggest that vitamin D insufficiency and deficiency are highly prevalent among healthcare workers. Health education regarding lifestyle modifications for this occupational group are warranted to improve their vitamin D status in the COVID-19 era.