On Sunday, Utah Jazz center Rudy Gobert, who tested positive for coronavirus (COVID-19) almost two weeks ago, posted this news about his condition on Twitter:

Just to give you guys an update, loss of smell and taste is definitely one of the symptoms, haven’t been able to smell anything for the last 4 days. Anyone experiencing the same thing?

— Rudy Gobert (@rudygobert27) March 22, 2020

Apparently, other people with COVID-19 have. Last week, for example, Frozen 2 actor Rachel Matthews (the voice of Honeymaren) reported on the fourth day of her confirmed case of COVID-19 that she had “randomly lost my sense of smell and taste.”

And it’s not just Americans with COVID-19 who are reporting experiencing anosmia (the medical term for a loss of smell) and ageusia (loss of taste). Writing for Forbes, infectious disease specialist Dr. Judy Stone relates this story of a friend in Italy:

One of the most unusual symptoms of coronavirus (COVID19) infection is the loss of a sense of smell and taste. I learned about this yesterday from a friend in Italy who I’ve been so worried about. She finally confessed that she likely had it two-three weeks ago and is normalizing. Symptoms included profound fatigue, fevers, and cough. Her most peculiar symptoms, however, were a profound loss of smell and taste. She sanitized her flat, but did not smell the bleach. She watched garlic browning on the stove, but could not smell it. Nor could she taste these strongly scented vegetables like garlic or fennel. Fortunately, all of her symptoms are resolving. She is one of the lucky ones.

The friend also told Stone that physicians in Italy have reported, anecdotally, that a significant proportion of their COVID-19 patients have similarly lost their sense of taste and smell.

“No studies have been done because these physicians are overwhelmed,” says Stone.

A sign to self-isolate

The anecdotal evidence from around the world is strong enough, however, for a group of British ear, nose and throat physicians to issue a statement over the weekend that asks all adults with sudden anosmia — even if they have no other symptoms — to self-isolate for seven days.

“We might be able to reduce the number of otherwise asymptomatic individuals who continue to act as vectors, not realising the need to self-isolate,” they point out.

Medical personnel who are treating people with anosmia should use personal protective gear and avoid doing nonessential procedures, the specialists add. Those precautions are urgent, they stress. Here’s why, as explained by New York Times reporter Roni Caryn Rabin, who interviewed Claire Hopkins, one of the authors of the statement and president of the British Rhinological Association:

[T]he virus replicates in the nose and the throat and an exam can prompt coughs or sneezes that expose the doctor to a high level of virus.

Two ear, nose and throat specialists in Britain who have been infected with the coronavirus are in critical condition, Dr. Hopkins said. Earlier reports from Wuhan, China, where the coronavirus first emerged, had warned that ear, nose and throat specialists as well as eye doctors were infected and dying in large numbers, Dr. Hopkins said.

On Sunday, the American Academy of Otolaryngology issued warnings similar to those of their professional peers in Great Britain. They said that in the absence of allergies or sinusitis, the loss of smell or taste — particularly the loss of smell — should be used as a screening tool for possible COVID-19 infection.

Such symptoms also “warrant serious consideration for self isolation and testing of these individuals,” they add.

Biologically plausible

It’s not entirely clear why COVID-19 is causing people to lose their sense of smell and taste, but there is a plausible biological explanation.

“Some viruses destroy the cells or cell receptors in your nose. Others infect the brain via the olfactory sensory nerves,” explains Stone. “Most disturbingly, this ability to infect the brain is thought to explain some of the cases of respiratory failure in COVID-19 infections.”

Fortunately, the anecdotal evidence suggest that people who recover from COVID-19 do eventually regain their sense of smell and taste, although that process may take several weeks.

Stone offers some advice for how individuals can determine if they have these symptoms.

“It’s easy to test for loss of smell with a variety of household items — citrus, soap, or cleaning supplies,” she says. “You can test taste with sweet, salty, sour, or bitter items.”

FYI: You can read the statement by the British ear, nose and throat specialists here and the one by their American counterparts here.