There’s no data suggesting that gargling prevents infection from the virus causing COVID-19. The SARS-CoV-2 virus is too new to know. But, in general, gargling might have modest preventive benefit for colds (and likely less so for the flu). Once someone has an upper respiratory infection, gargling is not a treatment for the infection. It would, at best, offer some degree of soothing of sore throat symptoms.

Cold and flu season runs from about October to May. As I write this, on March 19, we are still in the midst of the time of year when getting sick from viruses that cause colds and flu is common.