It was one of the most surprising symptoms of COVID-19, when this disease still had no name and we only knew it as “the coronavirus”.
The loss of smell that began then and has not yet been stopped, was something inexplicable that warned of the beginning of the infection and drove scientists crazy.
But now, almost two and a half years later, it seems that they are finally beginning to see the light at the end of the tunnel.
Researchers are beginning to learn how SARS-CoV-2 caused loss of smell.
Even many potential treatments to cure that loss are already underway. Some already in the clinical trial phase, including steroids and blood plasma.
Good news: Omicron does not produce as much anosmia
Anosmia was one of the words that because of the pandemic we had to learn. It means loss of smell, and in the first and tragic era of the “coronavirus” it affected, in the long term, more than half of those infected.
But the change has been important, and the data obtained in a survey with 616,318 people and published a few days ago, are quite significant:
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The people who had contracted the first variant of worry, which was baptized as Alpha although it was better known as a British strain, they had a 50% chance of suffering loss of smell, which scientists call chemosensory disruption.
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The probability dropped to 44% for the Indian variant, better called Delta,
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AND with omicronwhich arrived from South Africa, the loss of smell now only occurs in 17% of those infected.
Of course “just” is saying a lot. Because if we take into account the very high number of infections in the world, we could affirm that the loss of smell is still affecting many millions of people.
…And a bad one: Millions of people still do not recover their sense of smell
The chemosensory effects, the researchers say, continue to affect a high percentage of people who have not smelled since the early days of the pandemic.
And a study carried out last year showed that 46% of those who had had COVID-19, a year later, still had smell problems.
And 7% maintained the total loss of smell, or anosmia, more than a year later.
Do we know how SARS-CoV-2 takes away our sense of smell?
The first step in trying to find a remedy for the loss of smell was to try to locate the cause, which has never had a clear explanation.
The most widely held hypothesis from the earliest times showed that the virus attacks cells in the nose, called sustentacular cells, which are the ones that provide nutrients to odor-sensitive neurons.
But the investigation has not stopped and new discoveries continue to appear.
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A study conducted by Columbia University researchers on the cadavers of people who had died from COVID-19 found that although their neurons were apparently intact, their nuclei were jumbled and their internal architecture was completely unrecognizable.
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Other studies found a genetic mutation that was associated with an increased propensity to lose smell or taste. But it did not clear up too many doubts.
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Another study, which double-scanned the brains of 785 people, found evidence of lasting structural changes in the brains of people with smell loss, specifically in areas linked to the olfactory center of the brain.
Are there treatments to recover my sense of smell?
What there is are multiple clinical trials looking for something to cure this unpleasant and limiting ailment.
But it is still early and so far the only thing that most researchers recommend is smell training.
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Strong-smelling substances are brought up to the patient’s nose so they can smell them and try to identify them, over and over again. And with the repetition of this act, it is intended to promote the restoration of olfactory signaling.
The bad thing is that the method seems to work only with people who have partial loss of smell, and that is reduced to 1 in 3 affected.
steroids and plasma
Among the treatments that are being strongly explored, steroids appear in the first positions.
The reason is that they are drugs that reduce inflammation, and since COVID-19 is known to trigger extensive inflammation that could play a role in impaired smell…
But in practice the results have not ceased to be disappointing.
Another therapeutic possibility is platelet-rich plasma.
It is made from the patients’ own blood and is rich in biochemicals that could induce healing.
There are already a couple of studies whose percentage data could indicate that it works. But at the moment the numbers are so small that no big conclusions can be drawn.
In any case, a team in the United States is now launching a larger study.
A study on how to treat it is also underway. It has already been effective in other forms of loss of smell and an attempt will be made to see if it is effective in this one.
But to have the data from this study, what is left of 2022 and some of 2023 will be needed.
Unfortunately, as Nature says, for this disease there are no public funds that were used to get the vaccines, and the pace is very slow.