A new study adds to a growing pile of evidence that suggests losing your sense of smell and taste is an early sign of Covid-19.
While there has been anecdotal information about this link, these are the first empirical findings that make a strong connection, according to the researchers at the University of California, San Diego.
Other known symptoms of coronavirus infection include fever, fatigue, cough and difficulty breathing.
"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 study author Dr Carol Yan, an otolaryngologist and head and neck surgeon at UC San Diego Health.
Rapid sensory recovery
"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," Yan said in a university news release.
The study was published in the journal International Forum of Allergy & Rhinology.
The findings came from a survey of 262 patients with flu-like symptoms who underwent testing at UC San Diego Health from 3 March through March 29. Of those patients, 59 tested positive for Covid-19 and 203 tested negative.
Of the Covid-19 patients who reported loss of smell and taste, the loss was typically significant. However, the rate of recovery of smell and taste was high and usually occurred within two to four weeks of infection.
"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," Yan said.
Early or subtle symptoms
"Among the Covid-19 patients with smell loss, more than 70% had reported improvement of smell at the time of survey and of those who hadn't reported improvement, many had only been diagnosed recently," she said.
The return of smell and taste often matched the timing of recovery from Covid-19.
The researchers also found that people with a sore throat more often tested negative for Covid-19.
Most of the patients in the study had milder forms of Covid-19 and did not require hospitalisation or intubation.
The findings highlight the importance of identifying early or subtle symptoms of Covid-19 infection in people who may be at risk of transmitting the disease as they recover at home, Yan noted.
"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," she said.
UC San Diego Health now includes loss of smell and taste as a Covid-19 screening requirement for visitors and staff, as well as a marker for testing patients who may be positive for the coronavirus.