Researchers at the University of Georgia report that 10 seconds of contact with black tea deactivates 99.9% of COVID-19 in saliva.
This is important because the virus infects and replicates inside the oral passage through the oropharynx before reaching the lungs, according to researchers.
Typical concentrations of commercially available green tea, Mint Medley, Eucalyptus-Mint, and Raspberry Zinger teas were nearly as lethal to the SARS-CoV-2 virus in-vitro.
Virologist Malak Esseili and co-author Julianna N. Morris at the University of Georgia Center for Food Safety in the College of Agricultural and Environmental Sciences published their findings in the January issue of the peer-reviewed journal Food and Environmental Virology.
Curious about the widespread use of tea to treat respiratory ailments, Dr. Esseili purchased five grocery store teas and brewed infusions at two concentrations. Four teas showed preventative effects ranging from 68% to 90% reduction of the virus at the lower “drinkable” concentration.
She said the greatest preventative benefit was found immediately after mixing black tea with the live virus for 10 seconds and 60 seconds. Ten seconds was sufficient to render the virus harmless at concentrations of 40 mg per milliliter. The less concentrated “drinkable” teas were brewed for 10 minutes at 37 degrees Celsius. The tea for use as a gargle was brewed at a concentration four times greater than the drinkable infusion. All five tea varieties reduced the virus by 99.9% within 10 seconds when gargled.
The amount of tea polyphenols measured against the infectivity “showed a significant correlation in virus reduction.”
According to Esseili, the most potent effect was observed when the teas were introduced at the time of virus infection, suggesting a potential 'rapid at-home intervention' such as tea drinking or gargling.
“This could significantly reduce the infectious SARS-CoV-2 load in the oral cavity, potentially mitigating infection of the oral mucosa,” she said.
"Inactivating SARS-CoV-2 in the mouth and the throat matters because that potentially reduces the introduction of the virus to the lower respiratory system," Esseili said.
Having something accessible, easily prepared, and suitable for all the family would be ideal, Esseili said.
Clinical trials will be needed to demonstrate whether tea can benefit a patient ill with COVID-19, said Esseili, who adds that the “initial results are both promising and exciting for those looking to supplement medical care.”