Scientists and doctors noticed several weeks ago there seemed to be anecdotal evidence of a connection between the coronavirus and patients showing up with a decrease or complete loss of the sense of smell. They went to work studying the connection and say there's evidence that loss of smell is an indicator of COVID-19.
Dr. Ahmad Sedaghat, an associate professor with UC's College of Medicine and an UC Health physician specializing in diseases of the nose and sinuses, reviewed 19 studies on sinus and nasal disorders connected to the novel coronavirus.
He also worked with French physicians studying a possible connection.
"The study showed that, in patients who presented to their hospital complaining of new, sudden onset decreased sense of smell without any other nasal symptoms whatsoever, 94% of patients tested positive for COVID-19," Sedaghat says. "The other 6% all had a history that seemed awfully suggestive of COVID-19. For example, they were in contact with COVID-19 positive individuals."
In the French study, Sedaghat says, the vast majority of patients had no other symptoms of COVID-19.
Sedaghat's findings are reported in the journal Laryngoscope Investigative Otolaryngology.
It remains unclear where in the disease cycle anosmia (sudden loss of sense of smell) occurs or if it's an indicator of severity. Sedaghat says researchers are actively studying these questions.
"We're still doing a lot of epidemiologic studies trying to identify when exactly in the COVID disease course decreased sense of smell occurs. Does it happen primarily at the beginning of the disease course? Does it primarily happen in asymptomatic carriers? Can it happen later in the disease course; could it be a sign of resolution? We're just not sure."
Sedaghat says as the link came to light, doctors began to wonder if the loss of sense of smell might be an indicator someone who appeared asymptomatic was actually a carrier who might be unknowingly spreading the disease.
"At least in some populations, some fraction of these patients, they're walking around with no other symptoms at the time and they could potentially be spreading the disease to others."
How noticeable is the loss of smell? Sedaghat says it was profound enough that patients sought medical care about it.
The Nose Knows
The nose and naval cavity plays a major role in the spread of COVID-19, Sedaghat says. It's the main entry point for the disease and the primary point from which the virus is expelled.
"The amount of virus that's shed from the nose is dramatic, and it tends to occur primarily early in the disease course."
So keep those masks over your nose, not just your mouth.
Patients rarely experience other nasal symptoms, making it easy to distinguish between allergies or a cold and the virus, he says.
Putting This Information To Use And Next Steps
Sedaghat would like to see this information utilized by public health experts immediately. He says countries in Europe are already attempting to identify asymptomatic carriers by sense of smell loss and recommending they go into isolation.
Scientists also are trying to figure out where in the disease course anosmia occurs. Sedaghat is working with doctors in Europe to determine the severity of the anosmia cases.
The research is rapidly changing, Sedaghat points out. "We're getting more and more information and new insights with every passing day," he says, adding that new facts could emerge at any time.
UC Department of Otolaryngology-Head and Neck Surgery residents Dr. Isabelle Gengler and Dr. James Wang co-authored the study, along with Dr. Marlene Speth from Kantonsspital Aarau in Aarau, Switzerland.