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Nothing about the way she was feeling made her worry until that Monday morning, just over a week ago, when she went downstairs to feed her cat.

“I went down to my kitchen and opened a can of cat food and realized I couldn't smell it.”

The woman, who asked that she only be identified by her first initial “C” to protect her family’s privacy, had a sore throat and was feeling fatigued. But she had no fever, cough or shortness of breath, the now familiar symptoms of the coronavirus recognized by the Centers for Disease Control and Prevention. 

A healthy, energetic 60-year-old, C works as a project coordinator at a health clinic in Rhode Island. She doesn’t have direct contact with patients. Nobody in her office had tested positive for COVID-19, the illness caused by the coronavirus. And she says she’d been vigilant about washing her hands.

But when she still had no sense of smell on Tuesday, she said, she called her primary care doctor. Her doctor, who is affiliated with Brown University,  reported her case to the state Health Department. A nurse from the Health Department then scheduled C to be tested the following day.  “I was reassuring people, including especially my mother, that I didn't have any of the obvious symptoms of COVID-19 -- the fever, coughing,’’  C said, “so I was pretty convinced that it wasn't’’ the coronavirus.

Her test came back positive for COVID-19.

The loss of smell, or anosmia, is now being recognized by physicians around the globe as one of the telltale signs of COVID-19. On March 20, a group of British ear, nose and throat doctors cited evidence from South Korea, China and Italy in calling on adults who suddenly lose their sense of smell to self-isolate for seven days, even if they have no other symptoms. In South Korea, where testing has been more widespread, the doctors said in a statement , a loss of smell was the major presenting symptom in 30% of patients testing positive for COVID-19 who had otherwise mild cases.

“Anosmia has been described for COVID-19 as a symptom of the disease,’’  said Philip A. Chan, an infectious disease physician at Brown University. “It's something that physicians are aware of. And it's something that we are screening for. And certainly if patients have anosmia, it's a sign that they should be tested for COVID-19.”

Governor Gina M. Raimondo on Friday urged primary care providers to send more referrals for testing, saying that people who are sick should call their doctors because “the more we test, the better off we’ll all be.” The state last week doubled its testing capacity, she said, to more than 1,000 people per day.

But the state Health Department’s screening criteria to be tested do not include a loss of smell. Nor is it on the list of screening criteria recommended by the CDC or The World Health Organization, which lists “other symptoms” such as shortness of breath, aches and pains, sore throat, diarrhoea, nausea and a runny nose.

Joseph Wendelken, a spokesman for the state Health Department, said there’s not enough scientific data on the loss of smell and COVID-19 to include it in the state’s screening criteria. “It would not be unreasonable for a healthcare provider to screen for it,’’ he said in an email, “but other issues (like trouble breathing, fever, muscle aches, etc.) are much more prevalent, which is why we focus on them...At this point, anosmia is not one of the primary symptoms we are indicating that clinicians should be looking for.”

Some physicians say that needs to change. The American Academy of Otolaryngology published a statement March 22 calling for anosmia, or loss of smell, to be added to the list of screening tools for COVID-19. They want to alert doctors so that patients whose symptoms aren’t due to allergies or other infections can be tested for the coronavirus. And the organization has created a reporting tool to gather data from clinicians about cases of loss of smell, usually accompanied by a loss of taste, or dysgeusia, associated with COVID-19.

The lack of state or federal guidance on this emerging symptom means that people who may be infected with COVID-19 but who have none of the more common symptoms of the virus may not qualify for testing, assume they aren’t infected, and go on to infect others. 

Betha Wood had none of the common symptoms of the coronavirus. A 39-year-old hair stylist and owner of Salon Bianco, Wood was helping prepare dinner at a friend’s house on March 18 when she noticed she couldn’t smell the food. “I started sniffing you know, candles and anything I could find that had a smell,’’ she said, “and I realized I had absolutely no sense of smell. And I could barely taste anything.”

The day before, Wood said, she’d felt a strange burning sensation in her sinuses. But she has seasonal allergies, so initially she didn’t think much about it. Her chest “ached,’’ but she said she wasn’t having trouble breathing and was anxious about getting sick, so she wrote it off as a “stress response.”

On the morning of March 19, Wood said, she called her primary care doctor about an unrelated issue and mentioned that she couldn’t smell. But Wood said her doctor didn’t tell her to self-quarantine. As a precaution, Wood said, she closed her salon that day, four days before salons were ordered to close,  and stayed home. Three days later, still unable to smell, Wood said, she read a news story about British physicians reporting loss of taste as a symptom of COVID-19. Wood called her doctor back. “They had a nurse call me back and ask one series of questions,’’ she said. “And then a doctor called me back and asked me the second set of questions and gave me instructions.”

Wood said she was not told to get tested. (At the time, the testing in the state was limited to people who were hospitalized or health care workers and other people at high-risk of spreading the virus.) But she was instructed to self-quarantine for at least seven days after her symptoms had resolved. If she developed a fever, she needed to stay home for 72 hours after she was fever-free with no fever-reducing medications. To be safe, Wood said, she planned to self-quarantine for 14 days.  It took almost a week before Wood started to regain her sense of smell. That first day she made her favorite breakfast: scrambled eggs and sausage. 

For C,  who tested positive for COVID-19, the loss of smell was followed by other more debilitating symptoms: muscle aches, nausea and fatigue “to the point where it was really hard to get out of bed, even to stand up for more than a couple of minutes at a time.’’

Still, she feels fortunate that her illness is mild. And though losing her sense of smell is a “small thing,” she said, it has had a big impact on her emotional well-being. 

“Being isolated because you have COVID-19 is already really difficult,’’ she said. “And then not being able to taste or’s a sensory deprivation that made me, anyway, feel more alone.”

After 10 days, her sense of smell began to return. “For the first time yesterday I ate two good meals,’’ she said, “and I'm sure that being able to taste them had some part of it.”