New research Thursday aims to quantify a life-changing aftermath of covid-19: a persistent loss of odor, also known as anosmia. The study estimates that up to 1.6 million people in the United States have experienced chronic anosmia lasting at least six months after their coronavirus infection.
Anosmia can be caused by a variety of things, including respiratory virus infections such as covid-19. But it took some time before anosmia was recognized as a clear symptom of covid-19 – one that may even be more usually among mild cases. Often this odor loss is accompanied by a loss of taste, as the two senses are closely interdependent. Sometimes people can also experience parosmia or a distorted sense of smell that can make everyday scents smell of garbage, sewage or other rotten smells.
Studies have estimated that anywhere from 30% to 80% of covid-19 sufferers can develop some degree of anosmia. But research has shown that most (up to 90%) regain their sense of sniff in as little as two weeks, possibly because the infection do not usually to damage the olfactory nerve itself, but the cells that support it. Since so many people have got covid-19 in the United States, even a relatively rare complication like prolonged anosmia can still affect many people.
This new study, published Thursday in JAMA Otolaryngology – Head & Neck Surgery, appears to be one of the first to try to measure the number of chronic covid-related anosmia in the United States. The authors were forced to study the problem after seeing many of these patients in their clinics.
“In the last few months, my colleagues and I have noticed a dramatic increase in the number of patients seeking medical attention for odor dysfunction.” study author Jay Piccirillo, an otolaryngologist at Washington University in St. Louis and an editor at JAMA Otolaryngology, told Gizmodo in an email.
Piccirillo and his team estimated a number of cases, based on projections of covid-19 spread, the chances of someone developing anosmia from infection, and the likelihood of chronic anosmia. In the most likely scenarios, somewhere between 700,000 and 1.6 million Americans (in August 2021) have experienced a loss or a change in their sense of smell that lasted more than six months as a result of covid-19 so far, they found. This number includes those who have parosmia, although there are no specific numbers available for that group. It is possible that these numbers are an underestimation, the authors say, and the pandemic is not over – many more Americans may get covid-19 in the coming months.
There are treatments that are thought to improve a person’s chances of recovering from covid-related anosmia, such as odor training, and there are clinical trials ongoing now testing experimental treatments. But for those who are unlucky enough to still have trouble smelling things months down the road, the chances of recovery are small.
“Most cases (~ 90%) of viral associated anosmia disappear within two weeks – including covid. The prognosis for long-term olfactory dysfunction (ie> 6 months) is not good. Less than 20% can expect to recover the odor after 6 months , “said Piccirillo. Eventually, he added, about 5% of all anosmia cases will lose some or all of their sense of smell permanently.
There have been many direct and indirect effects of the pandemic, from millions of covid-19 deaths to re-flush of other diseases. However, permanent anosmia can be one of the most obvious lifelong consequences of infection. A recent study by French researchers this month even found that anosmia may be the long-term symptom most likely associated with a laboratory-confirmed case of covid-19. Long after the pandemic has disappeared, many people will no longer be able to enjoy certain basic pleasures in life, such as a delicious meal or the familiar scents of their loved ones.