A number of publications, such as The Lancet and JAMA, have been reporting anecdotal reports of the loss of smell and taste in patients with the disease caused by coronavirus, SARS-CoV-2 infection, also known as COVID-19. A new study presents empirical findings that strongly associate smell and taste dysfunction with COVID-19. Sore throat, they found, was more strongly associated with COVID-19 negativity.

When screening patients for COVID-19, clinicians often look for the most common symptoms of COVID-19: fever, cough, and difficulty breathing. The results of this study, published April 12 in the journal International Forum of Allergy & Rhinology, suggest that screeners ask patients about their senses of smell and taste.

Carol Yan, MD, a head and neck surgeon and otolaryngologist at UC San Diego Health served as lead author of the study. “Based on our study, if you have smell and taste loss, you are more than 10 times more likely to have COVID-19 infection than other causes of infection. The most common first sign of a COVID-19 infection remains fever, but fatigue and loss of smell and taste follow as other very common initial symptoms,” said Yan in a press release. “We know COVID-19 is an extremely contagious virus. This study supports the need to be aware of smell and taste loss as early signs of COVID-19.”

Study Investigates Chemosensory Dysfunction and COVID-19

A total of 1,480 patients complaining of flulike symptoms and expressing concerns about potential SARS-CoV-2 infection underwent COVID-19 testing at UC San Diego Health from March 3 through March 29. Of those, 102 tested positive and 1,378 tested negative.

The researchers surveyed the patients and received responses from 59 COVID-19-positive patients and 203 COVID-19-negative patients. Most of the respondents to the study had milder forms of the disease and did not require any hospitalization or intubation.

Of the COVID-19-positive respondents, 68% reported loss of smell and 71% reported loss of taste. In comparison, only 16 percent of the COVID-19-negative reported loss of smell and 17 percent complained of loss of taste. Patients that experienced sort throat tested negative for COVID-19 more often.

Smell and taste impairment, or anosmia and ageusia, respectively, were independently and strongly associated with COVID-19-positivity, with adjusted odds ratio [aOR] of smell impairment at 10.9, (95% confidence interval [CI]: 5.08‐23.5) and aOR 10.2 (95% CI: 4.74‐22.1) taste impairment. Sore throat, by comparison, was associated with COVID-19 negativity (aOR 0.23, 95%CI:0.11‐0.50).

The results of the study demonstrated not only the high prevalence of anosmia, but also the unique presentation of certain sensory impairments in COVID-19-positive patients. Those who reported anosmia and ageusia said the loss of smell and taste was typically profound, rather than mild.

The results also showed that the rate of smell and taste was high, and that recovery of those senses typically occurred within two to four weeks of infection. Of those who reported loss of smell associated with COVID-19, 74 percent said their anosmia resolved with the resolution of COVID-19. The return of smell and taste typically matched the timing of disease recovery.

“Our study not only showed that the high incidence of smell and taste is specific to COVID-19 infection, but we fortunately also found that for the majority of people sensory recovery was generally rapid,” said Yan. “Among the COVID-19 patients with smell loss, more than 70 percent had reported improvement of smell at the time of survey and of those who hadn’t reported improvement, many had only been diagnosed recently.”

To decrease risk of transmission of coronavirus, UC San Diego Health began including loss of taste and smell in their screening requirement for staff and visitors, and as a marker for testing patients.

Identifying early and subtle symptoms of COVID-19 infection in people who are otherwise asymptomatic may help reduce the spread of the disease.

“It is our hope that with these findings other institutions will follow suit and not only list smell and taste loss as a symptom of COVID-19, but use it as a screening measure for the virus across the world,” Yan said.

Other institutions are listing those as symptoms of COVID-19. In fact, the Centers for Disease Control and Prevention (CDC) now lists “new loss of taste or smell” on its Symptoms of Coronavirus page.