The five basic senses are bridges that connect humans to their living world. However, not having two of these senses could drastically impact a person's quality of life. Unfortunately, many COVID-19 survivors who lost their sense of smell and taste reported not getting it back even after months of recovering from the infection.
For people who experienced COVID-19-related loss of smell and taste, it could be demoralizing. They can no longer smell the familiar scent of loved ones or taste their favorite dish. Diane Ackerman, an author, and poet described the experience as "the heady succulence of life itself."
But importantly, it affects health, causing poor appetite and undesired weight loss, according to Harvard Medical School Publishing. It can even put people in existential threats by not being able to detect fires, gas leaks, or spoiled food.
When Will Sense of Smell and Taste Come Back After COVID-19?
According to the report of USA Today, researchers from the University Hospitals of Strasbourg in France followed recovered COVID-19 patients who experience the loss of smell and taste for one year and asked them to complete a survey every four months.
Researchers asked 51 out of the 97 patients in their survey to undergo objective testing to confirm the self-reported surveys. They found that 49 out of these 51 patients had fully recovered their sense of smell and taste after eight months.
Moreover, one out of two patients reported having recovered their sense of smell and taste, but the other one still could not smell by the end of the study. Those who did not undergo the objective testing all reported having back their sense after a full year since recovering from COVID-19.
"Our findings suggest that an additional 10% gain in recovery can be expected at 12 months, compared with studies with six months of follow-up that found only 85.9% of patients with recovery. This supports findings from fundamental animal research, involving both imaging studies and postmortem pathology, suggesting that Covid-19-related anosmia is likely due to peripheral inflammation," corresponding Marion Renaud wrote in the study.
He added that persistent COVID-19-related anosmia has a great prognosis with nearly complete recovery in one year. Additional data on long-term outcomes of people with the post-COVID-19 syndrome are needed for an informed prognostication and counseling.
They published their study, "Clinical Outcomes for Patients With Anosmia 1 Year After COVID-19 Diagnosis," in JAMA Network Open.
What Caused the COVID-19-Related Anosmia?
The reason behind the loss of smell in COVID-19 patients is difficult to understand. It is different from common colds or flu, where the sense of smell and taste are affected by nasal congestion and a stuffy nose which are not part of the symptoms of COVID-19.
Early on in the pandemic, scientists thought that SARS-CoV-2 might be infecting the olfactory neurons or perhaps using neurons to infect the brain. But studies show that this is unlikely because it appears that the virus attacks the helper cells of neurons in the nasal cavity and not the neurons themselves, MIT Medical reported.
These helper cells provide support to the cilia, which are finger-like structures on the surfaces of neurons. They are peppered with ACE2 receptors, through which the SARS-CoV-2 enters the body's cells.
On the other hand, there is lesser information about the loss of taste, which might be related to the sense of smell. But some COVID-19 patients also reported losing the chemical sensing on spicy food, which is moderated by pain-sensing nerves. Like the helper cells in the olfactory system, support cells in the tongue contain ACE2 receptors and some pain-sensing nerves in the mouth, making them susceptible to the virus.
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