Gargling some combination of warm water, salt, and vinegar has long been used as a means of relieving symptoms related to colds and flus, such as sore throats.
There is a claim that gargling with salt water or Vinegar will help ‘eliminate’ the COVID-19 coronavirus from the throat of an infected person’s system by preventing it from reaching the lungs via the throat:
There’s no evidence that it can help ward off or drive out infections from the COVID-19 coronavirus disease. And although the virus is said to replicate in the nose and nasal secretions, we’ve found nothing documenting the notion that the current coronavirus “remains in the throat for four days” and can be effectively expelled at the conclusion of that time period to keep it from reaching the lungs. (The incubation period for this virus, which is the time between when a person is exposed to the virus and when they start showing symptoms, has been estimated at about five days on average.)
The World Health Organization’s (WHO) website offers a page offering COVID-19 coronavirus disease advice for the public which addresses the substance of this rumor in an item about rinsing nasal passages (which are connected to the throat) with saline:
There is no evidence that regularly rinsing the nose with saline has protected people from infection with the new coronavirus.
There is some limited evidence that regularly rinsing the nose with saline can help people recover more quickly from the common cold. However, regularly rinsing the nose has not been shown to prevent respiratory infections.
Drinking sufficient water to stay adequately hydrated is generally good health advice at any time, but gargling with it (whether in plain form or as saline/vinegar) is of doubtful benefit for ‘eliminating’ the coronavirus once it has already taken.