A loss of smell or taste could be an early sign of infection with the pandemic virus, medical experts say, citing reports from several countries.

They could even serve as a useful screening tool, they say.

The idea of ​​a virus infection that reduces the sense of smell is not new. Viral respiratory infection is a common cause of loss of smell, because inflammation can interfere with air flow and the ability to detect odors. The sense of smell usually returns when the infection resolves, but in a small percentage of cases, loss of smell may persist after other symptoms disappear. In some cases, it is permanent.

Now there is “good evidence” from South Korea, China and Italy for the loss or deterioration of smell in infected people, says a joint statement by the presidents of the British Rhinological Society and ENT UK, a British group representing the ear, nose and throat doctors. In South Korea, about 30 percent of people who tested positive for the virus have cited loss of smell as their main complaint in other mild cases, they wrote.

So it could be useful as a way to screen infected people without other symptoms (fever, cough, and shortness of breath) of the new coronavirus, they wrote.

A similar proposal was published Sunday by the American Academy of Otolaryngology – Head and Neck Surgery. He noted anecdotal evidence of “rapid accumulation” around the world that the pandemic virus can cause not only loss of smell but also a decrease in the sense of taste. So the appearance of those symptoms in people with no other explanation should alert doctors to the possibility of a Covid-19 infection, the group said.

South China Morning Post, in an article published Wednesday, also highlighted studies and observations in several countries that indicate that a significant number of patients experience a loss of smell.

‘There is no solid evidence at the moment’

Maria Van Kerkhove, an outbreak expert at the World Health Organization, told reporters on Monday that the UN health agency is investigating whether loss of smell or taste is a defining feature of the disease.

Dr. Eric Holbrook, a nasal and sinus disease expert at Massachusetts Eye and Ears Hospital in Boston, said the reports have been a hot topic among researchers and doctors. But “we have no strong evidence at this time” on how often odor loss occurs in people infected with the pandemic virus, he said in an interview Monday.

Holbrook said reports he has seen suggest that the sense of smell returns in a couple of weeks, but how long it will last has not yet been firmly established.

He also said that it is difficult to assess reports of loss of taste because people with an altered sense of smell often report loss of taste, which is technically different from a deficiency of taste.

Holbrook said he is trying to establish a study of smell in people being tested for coronavirus in Boston-area hospitals.