The research published in JAMA Otolaryngology-Head & Neck Surgery estimates that between 700,000 and 1.6 million people in the US who had Covid-19 have lost their sense of smell or have had a change in their sense of smell that lasts for more than 6 months. This is likely an underestimate, the authors of Washington University School of Medicine in St. Louis said.
“These data suggest an emerging public health problem of OD and the urgent need for research focused on the treatment of COVID-19 COD,” the study said.
“With the long-term burden of disease from this, we’re going to be dealing with this for literally decades,” said John Hayes, director of the Sensory Evaluation Center at Penn State’s College of Agricultural Sciences. Hayes did not participate in this investigation, but did conduct research in the area.
He thinks the estimated number of people in the study with this problem is conservative and the problem could affect many millions more.
“It’s really a result of appetite and social relationships, as people who have lost their sense of smell may not be able to detect if they have body odor, and it could also affect diet,” Hayes said.
Hayes said his research with Covid-19 patients has shown that they have experienced three different types of long-term olfactory disorders.
Some lose or have a decreased sense of smell. Some have a poor sense of smell, where instead of flowers, for example, someone would smell foul-smelling feet. Others may have what Hayes calls a sort of “ghost limb syndrome” for sense of smell, where people smell things that aren’t there, such as a lingering chemical or burning odor.
dr. Sandeep Robert Datta, a neurobiologist at Harvard Medical School who has studied why people with Covid-19 lose their sense of smell, said this is an important line of research.
“We’ve never really made a formal estimate of how many people are struggling with this,” Datta said. “This is truly an unusual event in terms of olfactory dysfunction and an unprecedented consequence of a pandemic never seen before.”
“After that, there’s still a lot of mystery about what’s going on and in a lot of labs, including mine, we’re continuing to work on this problem,” Datta said.
Understanding how Covid-19 has distorted a person’s sense of smell will be important for scientists to determine how they can help regain the sense of smell, if it doesn’t return on its own.
“I recently had a patient call me and ask what could be done and frankly I don’t have any good recommendations yet,” Hayes said.