Until recently, loss of smell and taste was one of the many symptoms anecdotally linked to COVID-19. Now, researchers have reported the first empirical findings that strongly associate sensory loss with COVID-19 and further link a faster recovery among those who experienced such sensory loss.
Published in the journal International Forum of Allergy & Rhinology, the study was conducted by researchers from the University of California (UC) San Diego Health.
"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 Dr Carol Yan, MD, an otolaryngologist and head and neck surgeon at UC San Diego Health. "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."
For the study, researchers surveyed 1,480 patients with flu-like symptoms and concerns regarding potential COVID-19 infection who had undergone testing at UC San Diego Health between 3rd March and 29th March. Amongst those surveyed, 102 patients tested positive for the virus, while 1,378 tested negative. The study includes responses from 59 COVID-19 positive patients and 203 COVID-19 negative patients.
Dr Yan stated that the study demonstrates a high prevalence and unique presentation of certain sensory impairments in patients positive with COVID-19. Among those participants who reported loss of smell and taste, the loss was typically recorded to be profound and not mild. But, encouragingly, 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,” explained Dr 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.”
Researchers found that sensory return, typically, matched the timing of disease recovery. More interestingly, they found that persons who reported experiencing a sore throat more often tested negative for COVID-19.
Implementing the findings from this study, UC San Diego Health now includes loss of smell and taste as a screening requirement for visitors and staff, as well as a marker for testing patients who may be positive for the virus.
Other well-established symptoms of COVID-19 include fever, fatigue, cough and difficulty in breathing. Participants in this study were most often persons with milder forms of COVID-19 infection who did not require hospitalisation or intubation. Dr Yan stresses that the findings underline 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 recuperate within the community.
“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,” said Dr Yan.
