On its own, green tea extract has not been found to prevent infection by the coronavirus or to provide effective therapy against the COVID-19 disease resulting from an infection.
The extract contains a micronutrient, epigallocatechin gallate, that has shown promise in acting against some other viruses. A study published in June concluded that the chemical could be a candidate for further evaluation for use against the coronavirus. No research so far has proved its efficacy against the coronavirus.