Coffee and green tea consumption with the risk of COVID-19 among the vaccine recipients in Japan: a prospective study

Background: While coffee and green tea have been suggested to have immunoprotective effects, it remains elusive whether they can decrease the risk of COVID-19. Objective: We prospectively examined the association between coffee and green tea consumption and the risk of COVID-19 among mRNA vaccine recipients during the epidemic of the Omicron variant. Method: Participants were 2,110 staff (aged 18 to 76 years) of a large medical facility in Tokyo, who attended a serosurvey in June 2022, predominatly received >= 3 doses of vaccine, and were followed for COVID-19 until December 2022. Coffee and green tea consumption was ascertained via a questionnaire. COVID-19 was identified through the in-house registry. Cox proportional hazards model was used to estimate the hazard ratios (HRs) of COVID-19 across the categories of beverage consumption. Result: During 6 months of follow-up, 225 (10.6%) cases of COVID-19 were identified. Contrary to the expectation, higher consumption of coffee was associated with a significant increase in the risk of COVID-19; multivariable-adjusted HRs (95% CI) was 1.00, 0.92 (0.62-1.35), 1.48 (0.99-2.22), and 1.82 (1.20-2.76) for <1 cup/day, 1 cup/day, 2 cups/day, and >= 3 cups/day, respectively (p trend=0.003). Green tea consumption was not significantly associated with the risk of COVID-19. The association with coffee was attenuated if serologically detected infection was added to the cases. Conclusion: In a cohort of Japanese hospital staff who received COVID-19 vaccine, higher consumption of coffee was associated with an increased risk of COVID-19 during the epidemic of the Omicron variant. There was no evidence of a significant association between green tea consumption and COVID-19 risk.