Correlations betweenper capitagreen tea consumption and COVID-19 morbidity/mortality: comparing the strength before and after Omicron emergence

Purpose There is rapidly growing in vitro pharmacological evidence suggesting preventive/therapeutic potential of green tea and its constituent EGCG in battle with COVID-19. The aim of this study was to analyze time course of previously reported correlations between per capita green tea consumption and COVID-19 morbidity/mortality with a focus on comparing periods of time before (year 2021) and after (years 2022-2024) emergence of Omicron variant. Methods Correlations between per capita green tea consumption and COVID-19 morbidity/mortality were calculated using multiple regression models in a subset (n=84) of countries/territories worldwide with HDI above 0.55. Strength of the correlations for several dates in 2021 - 2024 was compared. Results Higher per capita green tea consumption was associated with lower COVID-19 morbidity and mortality. Statistically significant correlations were observed in 2021, 2022, 2023 and 2024. As compared to 2021, the strength of both correlations was decreased during 2022-2024 period. On average normalized to 2021 strength of correlation between per capita green tea consumption and COVID-19 morbidity decreased to 0.60, while normalized strength of correlation between per capita green tea consumption and COVID-19 mortality decreased to 0.83. Conclusion Overall, the results of this study are in line with in vitro pharmacological evidence. Though indirectly, these results at epidemiological level support the idea that green tea consumption may have not only preventive, but also therapeutic value in relation to COVID-19. Nevertheless, because of limitations of this study, this idea still should be considered as a hypothesis requiring further assessment.