Loss of smell in coronavirus infection: Harvard scientists uncover the reason for this anosmia!

Loss of smell comes early in COVID-19 infection and it is also a common symptom of the infection. In fact, Western governments have told people who have loss of the sense of smell to self-isolate themselves to protect others. Why and how coronavirus causes this symptom was not clear until now. Harvard researchers have studied this complaint in depth and have found out how this happens in this deadly infection.

Loss of smell and coronavirus infection

Loss of smell occurs as one of the first and common symptoms in coronavirus infection. CDC has listed it in its common symptoms of COVID-19. But what exactly happens that leads to this loss was not clear until now. Scientists from Harvard Medical School started studying the changes that the virus causes in those who report anosmia as one of their primary complaints. And they found that the virus causes damage to not the sensory neurons that carry the sense of smell to the brain.

Loss of smell in COVID-19 [Source: Medscape]
Instead, the virus attacks the cells that gives metabolic and structural support to these sensory neurons. Certain other stem and blood vessel cells are also affected.

Is anosmia permanent in coronavirus infection?

Since the nerve ends are not affected due to coronavirus infection, the virus will not cause a permanent loss of the sense of smell in these patients. Sandeep Robert Datta, one of the study authors is a Professor at neurobiology department at Harvard Medical School. He said:

“Our findings indicate that the novel coronavirus changes the sense of smell in patients not by directly infecting neurons but by affecting the function of supporting cells.”

Loss of smell in COVID-19 [Source: Sky News]
He added:

“I think it’s good news, because once the infection clears, olfactory neurons don’t appear to need to be replaced or rebuilt from scratch.

“But we need more data and a better understanding of the underlying mechanisms to confirm this conclusion.”

Hence the smell loss is temporary and this is a heartening news for COVID-19 patients.

Anosmia and its stats in CVOID-19 infection

The loss of the sense of smell in patients of coronavirus infection is 27 times higher than those who do not have the infection. The likelihood of these patients to have fever, cough, or respiratory issues is only 2.2 to 2.6 times that of others.

Loss of smell in COVID-19 [Source: Sky News]
Other viral infections can also cause anosmia. But the anosmia of COVID-19 recovers in weeks while that in other infections take a longer time, even months to recover. Also, anosmia of other viral infections occurs with a stuffy nose. But in case of COVID-19, it can occur even without a stuffy nose. Dr. Sandeep states that knowing how anosmia can happen in COVID-19 would aid its treatment. He said:

“Anosmia seems like a curious phenomenon, but it can be devastating for the small fraction of people in whom it’s persistent.

“It can have serious psychological consequences and could be a major public health problem if we have a growing population with permanent loss of smell.”

Also, read King’s College of London study reveals six different types of coronavirus symptoms cluster with varying disease severity!