Loss of Smell in Long COVID-19 Explained

Many people fail to regain their sense of smell after battling COVID-19. Being unable to smell freshly cooked lasagna can be a pain, and scientists finally have an explanation for the symptom. COVID-19 has changed our lives since it arrived in 2020. From high fevers to incessant coughs, the respiratory virus hunted the lives of many individuals. Even after recovering from the disease, some fail to regain their sense of smell- and now scientists have discovered why.

Why do people lose their sense of smell from COVID-19?

Research conducted by Duke Health revealed that the main reason behind the loss of smell derives from a continuous immune strike on olfactory nerve cells and a diminished number of those cells. According to the journal Science Translational Medicine, many have not fully recovered after COVID-19, including regaining their sense of smell. Scientists, while researching anosmia, also liked other long COVID-19 symptoms such as fatigue, shortness of breath, and brain fog.

“One of the first symptoms that have typically been associated with COVID-19 infection is loss of smell,” said Bradley Goldstein, M.D., Ph.D., senior author and associate professor in Duke’s Department of Head and Neck Surgery and Communication Sciences and the Department of Neurobiology.

"Fortunately, many people who have an altered sense of smell during the acute phase of viral infection will recover smell within the next one to two weeks, but some do not,... We need to better understand why this subset of people will go on to have persistent smell loss for months to years after being infected with SARS-CoV2."

Bradley Goldstein, M.D., Ph.D.

The research, conducted by Goldstein and other colleagues from Duke, Harvard, and the University of California-San Diego, examined olfactory epithelial samples from 24 biopsies, with nine patients experiencing loss of smell from COVID-19. The biopsy research utilized single-cell analyses as a team with Sandeep Datta, M.D., Ph.D., at Harvard University, and found an extensive penetration of T-cells in an inflammatory response in the olfactory epithelium. Not only did the olfactory epithelium, where smell nerve cells are, have inflammation, but olfactory sensory neurons decreased, feasibly due to the injury of continuous inflammation. “The findings are striking,” Goldstein said. “It’s almost resembling a sort of autoimmune-like process in the nose.”

Moving forward, it is crucial scientists learn what sites are harmed and which cell types are linked in the process to start treatments. Goldstein said the team was motivated as the neurons seemed to have the self-repairing ability even after a long immune fight. “We are hopeful that modulating the abnormal immune response or repair processes within the nose of these patients could help to at least partially restore a sense of smell,” Goldstein said, noting this work is currently underway in his lab. This research could also lead to more studies regarding other long COVID-19 symptoms.

What are some other long COVID-19 symptoms?

Many people get through COVID-19 without needing hospitalization. However, many continue to undergo symptoms even after recovering from COVID-19. Even those who had mild symptoms can develop lingering symptoms after recovery. These ongoing health complications are often referred to as post-COVID-19 syndrome or long COVID-19. Long COVID-19 refers to those with ongoing symptoms for more than four weeks. It can even linger for months or years after recovery.

Some common symptoms may include fatigue, fever, breathing problems, joint or muscle pain, and digestive symptoms. However, it is difficult to tell if all symptoms result from COVID-19 or are merely preexisting medical conditions. It is important to get your symptoms checked out by medical professionals if they do not seem to improve over time.

What should you do if you get infected with COVID-19?

With over 100 million cases of COVID-19 just in the United States, it is important to know what to do if you become infected. If you test positive for COVID-19, isolate yourself to prevent spreading it to others. You can take over-the-counter medications depending on your symptoms and rest to reduce your symptoms. If symptoms continue or become worse, seek medical help, such as taking antiviral treatments from medical professionals. The U.S. Food and Drug Administration has authorized antiviral medications to treat COVID-19 in some cases, including Paxlovid, Veklury, and Lagevrio.

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