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'Profound' smell loss is a common COVID-19 symptom, study confirms

woman smelling flowers
(Image: © Shutterstock)

A new study supports the notion that loss of either smell or taste may be an early warning sign of COVID-19.

Anecdotal accounts of smell and taste loss associated with COVID-19 have been reported worldwide, but without formal studies, scientists could not determine how common the symptom was among those infected. Now, a new study published online April 12 in the journal International Forum of Allergy & Rhinology has found that smell and taste loss appear to be common initial symptoms in patients with mild infections. 

People with smell loss can often still sense different tastes, like saltiness or sweetness, but cannot identify specific flavors, according to the medical reference site Merck Manual. Therefore, people with smell loss often report losing their sense of taste, as well.

"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," Dr. Carol Yan, an otolaryngologist and head and neck surgeon at the University of California, San Diego Health, said in a statement

While fever is still the most common first symptom of COVID-19, "this study supports the need to be aware of smell and taste loss as early signs of COVID-19," Yan said. Along with fatigue, smell and taste loss appear to be common first symptoms in a sizable group of patients, she added.

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Yan and her colleagues screened data from 1,480 patients with flu-like symptoms who underwent COVID-19 testing at UC San Diego Health in March. Of 102 patients who tested positive for the virus, 59 participated in the smell-loss study. An additional 203 people who tested negative also participated in the study, allowing the researchers to discern whether smell loss was fairly unique to COVID-19 patients.   

Of the COVID-19-positive patients in the study, about 68% said they experienced smell loss and 71% reported taste loss, as compared with 16% and 17% of negative patients, respectively. Among the COVID-19 patients with smell or taste loss, the decrease in sensation was often "profound, not mild," according to the UC San Diego statement. However, the majority of patients recovered their sense of smell and taste within about 2 to 4 weeks, around the time they'd recovered from infection. 

"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," Yan said. 

No participants in the study required hospitalization or invasive breathing support, such as intubation. If social-distancing measures were not in place, such individuals could potentially spread the infection to others in their communities, despite not experiencing intense symptoms. Smell and taste loss should be noted as potential signs of COVID-19 in people who otherwise feel well, given that those with mild symptoms contribute heavily to the virus' spread, Yan said.

"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.

Originally published on Live Science. 

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  • Wanda
    Intriguing symptoms, and very well worth screening for. Do we know what mechanism(s) of the virus might cause such an unusual loss of senses? Just wondering if such knowledge could open additional pathways to quick diagnosis and treatment.
    Reply
  • hebden
    I wonder if the crazy severe headache interferes with sensory centers in the brain? Since I had no idea I was having the COVID 19, and was demanded back at work after only 2 days off (4 total in bed) when I lost my sense of smell I thought my age was contributory, since I get a lot of age discrimination at work. After 2 months I'm able to smell Easter lilies but not to discriminate subtle food flavors. People suffering the virus need to have their confidence built up to overcome it ; knowing this is typical will help regain strength for healing. It can do a number on us psychologically as it makes one feel very weak very quickly - like loosing balance - and can literally knock you off your feet.
    Reply
  • Wanda
    hebden said:
    I wonder if the crazy severe headache interferes with sensory centers in the brain? Since I had no idea I was having the COVID 19, and was demanded back at work after only 2 days off (4 total in bed) when I lost my sense of smell I thought my age was contributory, since I get a lot of age discrimination at work. After 2 months I'm able to smell Easter lilies but not to discriminate subtle food flavors. People suffering the virus need to have their confidence built up to overcome it ; knowing this is typical will help regain strength for healing. It can do a number on us psychologically as it makes one feel very weak very quickly - like loosing balance - and can literally knock you off your feet.

    A couple of days ago I turned suddenly and lost my balance, triggering an ankle break and subsequent metatarsal fracture in my foot. My insurance "allowed" me to go to Urgent Care, where they vetted my coverage before allowing me to be seen by a provider. I'm now immobilized and struggling to stand to cook or even get to the bathroom. Of course our brain function is being affected! Our bodies function as a system, and an insult to one part will resonate to all the other parts. I detest our health care NON-system, which basically forces an individual to PROVE an injury or illness, even if the person has "insurance," and throws the uninsured under the bus. If any good comes of this plague, let it be basic health/injury care for all, insurance companies be danged.
    Reply
  • hebden
    I'm in Canada where I have been paying a premium and supposedly have additional coverage through employment but in fact can not access medical care; apparently there are not enough doctors and very difficult to see one who speaks English. When I was so sick I couldn't talk for 5 days but went to work and was soon sent home home on the 5th day. I waited 8 weeks for a doctor appointment and was told the first week of February not to go to ER with the flu. The health authority simply avoids testing here so many positives for COVID 19 have gone unreported.
    Reply