People who had lost their sense of smell after catching covid-19 partly regained it following the injection of blood cells called platelets into their noses, which could help to improve their quality of life.
Since the beginning of the pandemic, a loss or change to your sense of smell or taste has been considered a common covid-19 symptom.
鈥淭he SARS-CoV-2 virus enters cells in the nose, causing inflammation that can damage neurons, the cells that detect smells,鈥� says at Stanford University in California. But the symptom has become less common with newer variants, she adds.
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Most people spontaneously regain their sense of smell within a few months, while others recover after receiving a commonly recommended type of therapy called . This involves regularly sniffing different odours, such as coffee and lemons. 鈥淏ut that training doesn鈥檛 work for a huge number of people,鈥� says Patel.
In search of another treatment, Patel and her colleagues turned to a therapy that seems to of tissues, including skin and the cartilage in joints. It involves collecting a person鈥檚 blood and filtering out plasma 鈥� a clear yellow liquid that contains platelets, blood cells that produce regenerative proteins 鈥� before injecting this into the affected area.
To put it to the test, the team randomly assigned half of 32 people with covid-19-related smell loss to receive three platelet injections over six weeks, along with daily smell training. The remaining participants had the same treatment, except the injections were made up of saline. Both groups had an average age of 50.
At the start of the study, the researchers found that the participants could identify around half of 40 odours, such as pineapple and shoe leather.
One year later, the participants did the same test. Those who received the platelet injections could detect nine more odours than they could at the start, on average. 鈥淢any patients returned to tell me of their joy in being able to smell special things 鈥� their favourite flower, the smell of fresh bread, being able to smell their new baby grandchild,鈥� says Patel. The saline group only identified an average of one extra smell.
鈥淚t鈥檚 very encouraging 鈥� most people [in the platelet group] saw a benefit that would improve their quality of life,鈥� says at the University of Dresden in Germany. But larger studies should confirm the results and pinpoint how long the benefits last, he says.
Still, the results have prompted Patel, a clinician, to offer the therapy to people with covid-19-related smell loss who she treats. Another clinic in the UK plans to roll it out in early February.
International Forum of Allergy & Rhinology
