Once a hallmark sign of many new coronavirus infections, it can sometimes be more reliable than flu-like symptoms when sniffing out people with the virus. early in the pandemic — it was a sudden loss of smell and taste. However, as research progresses, the condition has become much less common, suggesting that only a small percentage of new patients reported it last year.
The findings were derived from the following analyses. Extensive dataset Medical records collected by the National Institutes of Health for COVID-19 researchers nationwide.
“In the past, people were fully aware that if they had a cold and lost their sense of smell, they could potentially have COVID-19. You can’t,” says Dr. Evan Reiter, VCU Health’s medical director. The Center for Smell and Taste Disorders told CBS News.
Led by the writer studywhich published Published in May in the journal Otorhinolaryngology Head and Neck Surgery, it investigated the probability that COVID-19 patients also report loss of smell and taste.
A condition known as chemosensory loss occurred in an estimated 50% of cases early in the pandemic, but the latest research suggests its prevalence is only 3% to 4% in recent Omicron waves. increase.
The study is one of the latest to reveal how the symptoms caused by the virus have changed. new variant Immunization against infectious diseases and prior vaccination provide protection that early patients lacked.
Researchers at University College London reported. in research Last week, it was announced that the rate of cases reporting loss of taste and smell has dropped significantly since the emergence of the Omicron strain in 2021.
As more worrying variants emerged, “SARS-CoV-2 symptoms gradually mimicked other respiratory symptoms. The more contagious Omicron strain was significantly associated with increased coughing and sneezing.” was,” the study authors wrote in the journal Scientific Reports.
A Path to New Treatments?
Scientists now have more clues as to why many patients failed to regain their sense of taste and smell after infection early in the pandemic.
A team of researchers led by Dr. Bradley Goldstein of Duke University and Dr. Sandeep Dutta of Harvard University reported last year Even after the virus has already died down, the mounting immune response appears to still be targeting nerve cells in the nose.
Volunteers allowed doctors to scoop up a small tissue sample from high on the nose, which was rushed back to the lab to be washed and filtered.
they were supplied to instrument This allows samples to be analyzed down to single cells. Comparing these with data from other patient samples without this type of smell loss revealed signs of ongoing inflammation driven by her T cells in the immune system. This represented the first living confirmation of an influential theory about long-term COVID-19 olfactory loss, which was largely based on autopsy and animal experiments.
“Long-term COVID-19 olfactory loss biopsies show an overall reduction in intact olfactory sensory neurons and nerve cells,” said Goldstein, an associate professor at Duke University’s School of Medicine. “This suggests that it is likely to continue to cause ongoing damage or impede repair.” told CBS News about neck surgery and communication science.
Goldstein said their findings were consistent with those seen driving other vehicles. persistent symptoms Recalling meetings with other researchers convened by the NIH RECOVER program, I reported on the long-term situation of COVID-19 patients.
“I think a common theme is emerging that much of it, whether it’s the kidneys, the heart, or the brain, seems to be mediated by the immune system. That’s one of the big findings of our paper. It was,” Goldstein said.
This could pave the way for new therapies that could give the body room to repopulate neurons for olfaction by directly suppressing the immune response.
“I think this is where the field of smell loss needs to move more broadly and in the direction of which areas could be targeted by drugs and potentially promote neuronal regeneration and recovery.” said he.
The NIH recently announced that it has launched Enroll volunteers in clinical trials There are several treatments for long-lasting COVID-19 symptoms, but none specifically for smell loss.
“Patients are experiencing a number of symptoms,” the agency said in a statement. “Interventions currently being tested or being tested may affect many of these symptoms, including loss of smell and taste.” added.
Olfactory training and nasal injection
So far, doctors have some options Attempt to treat patients who still suffer from loss of sense of smell.
In addition to impacting quality of life, such as turning once-delicious food into an unpleasant taste, Reiter said patients are facing a range of new challenges as they battle this long-running COVID-19 problem. rice field.
“The nose is like an early warning system for smoke and fire, but it’s hard to detect things like gas leaks, or even whether food is spoiled,” Reiter said. says.
Common starting points for treatment are: Olfactory trainingwhich works by repeatedly exposing the damaged olfactory nerves in the nose to different categories of pleasant odors.
One drug therapy being tried is steroids, but Reiter said evidence that they work remains scant.
Reiter said the approach shows some promise in a pilot study uses a platelet concentrate obtained from the patient’s own blood and may be able to regenerate tissue after being injected or dipped into the nose.
But treatment can be risky, and many patients eventually regain their sense of smell with little intervention from their doctors, the writer said.Ann previous research Reiter’s group found that only 7.5% of patients had no improvement in their sense of smell over the years.
“A lot of the time it’s really just time. The nerves can recover,” Reiter said.
