TORONTO -- Evidence is mounting that the sudden loss of the sense of smell and/or the sense of taste may be a sign of COVID-19 infection.

Cases of otherwise asymptomatic patients reporting an inability to detect odours and then testing positive for the new coronavirus have been reported in many of the countries hit hardest by the pandemic, including South Korea and Germany.

Though these claims have not yet reached the stage of peer-reviewed research, two British doctors' groups found them worrying enough last week to call for governments to require anyone who loses their sense of smell to self-isolate.

Since then, other medical experts have suggested that the virus may also be able to affect a second sense: taste.

The American Academy of Otolaryngology proposed, on March 22, that three conditions related to the loss of smell and taste be added to COVID-19 screening criteria, saying "anecdotal evidence is rapidly accumulating from sites around the world that anosmia and dysgeusia are significant symptoms associated with the COVID-19 pandemic."

Nadine Dorries, the United Kingdom's health minister, has said that she lost both senses as a "side effect" of her COVID-19 infection.

"Eating or drinking warm or cold, that's all I can tell," she tweeted March 19.

The World Health Organization (WHO) does not list the loss of the ability to either smell or taste as known symptoms of COVID-19, but has been watching closely as experts in several countries study the issue.

Asked about the reliability of the claims at a press conference on Monday, the head of the WHO's emerging diseases unit told reporters that she had seen "quite a few reports" of patients losing one or both senses in the early stage of infection.

"This is something that we need to look into to really capture if this is one of the early signs and symptoms of COVID-19," Dr. Maria Van Kerkhove said.

"We don't have the answer to that yet."