According to a 2022 survey, about 15% of people who experienced smell loss from COVID-19 continued to have problems six months later.
That’s roughly 9 million people in the U.S., and the number is growing.
In a study from Stanford Medicine, scientists found a new way to treat smell loss in long COVID.
They tested a new treatment for long-term, COVID-19-related smell loss using injections of platelet-rich plasma derived from a patient’s own blood.
They found in a trial of 26 participants, those who received the treatment were 12.5 times more likely to improve than patients who received placebo injections.
Platelet-rich plasma is a concentrated form of plasma, the liquid portion of blood, with blood cells and other blood components removed. It’s rich in platelets and, most importantly, growth factors—compounds known to help regenerate tissue.
Platelet-rich plasma has been purported to treat mild arthritis when injected into joints, reduce wrinkles when used on the face, and even regrow hair when injected into the scalp.
The team found that COVID-19-related smell loss also was a neurological problem, in which long-term effects of the virus prevent nerves deep in the nasal cavity from regenerating correctly.
These nerves connect to the brain and normally regenerate every three to four months.
In the study, all participants had confirmed past COVID-19 infections and persistent smell loss lasting between 6 and 12 months.
They also had to have already tried other treatments such as olfactory training and steroid rinses.
Half the participants received platelet-rich plasma injections into the tissue deep inside their nasal cavity every two weeks for six weeks, while the other half received placebo injections (of saline) on the same schedule.
Neither the participants nor the researchers knew who received what.
When the researchers checked in with the participants three months after their first injection, those in the platelet-rich plasma group scored on average 6.25 points higher than they did before treatment, which was 3.67 points greater than the placebo group.
They gained most in their ability to tell different odors apart, known as smell discrimination.
At three months, 57.1% of the platelet-rich plasma group had shown a clinically significant improvement, compared with just 8.3% in the placebo group.
The improvements in the placebo group could in part be due to a placebo effect, but they could also suggest that some spontaneous recovery can happen even after six months.
COVID-19 has brought attention to post-viral smell loss, and perhaps more appreciation of the role smell plays in our daily lives.
Though this study did not evaluate taste loss, the recovery of smell likely also would help with the recovery of taste.
If you care about COVID, please read studies about how vitamin B may help fight COVID-19, and new therapy from bananas may help treat COVID-19.
For more information about COVID, please see recent studies about new evidence on rare blood clots after COVID-19 vaccination, and results showing inexpensive, readily available drug that may treat COVID-19.
The study was conducted by Zara Patel et al and published in the International Forum of Allergy and Rhinology.
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