Feb. 9, 2022

The Loss of Smell and COVID-19

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COVID-19 has a wide range of symptoms, and it seems like new ones are discovered or experienced daily. The obvious and most common ones are not all that different than a common cold though. They can include feeling tired, sluggish, coughing, or even a fever. However, an array of other symptoms has presented themselves and, in some cases, are lingering even after the infection has gone.

One such symptom associated with the COVID-19 infection is the loss of smell. Generally, this development has not been associated with a stuffy nose and congestion though. Rather, some people are reporting their sense of smell is highly diminished or gone entirely.

The development drew plenty of interest from scientists and medical professionals. They wanted to determine how the virus functioned and the long-term effects it could have on the body. Researchers are now closer to understanding why some people lose their sense of smell after contracting the virus. Efforts to better understand how it works are shedding light on other lingering effects of COVID-19 as well.

Ability to Smell with the COVID-19 Infection

The research conducted by scientists with NYU Grossman School of Medicine and Columbia University explores how the infection impacts golden hamsters. They also utilized and examined olfactory tissue from 23 human autopsies. These subjects were chosen due to tests on living human beings being considered inhumane.

According to NYU Langone Health, experiments performed by the research team revealed "the presence of the virus near nerve cells (neurons) in olfactory tissue brought an inrushing of immune cells, microglia, and T cells that sense and counter infection." The report went on to say that "Such cells release proteins called cytokines that changed the genetic activity of olfactory nerve cells, even though the virus cannot infect them."

For the majority of people, these symptoms last for the duration of there illness. However, Becker's Hospital Review states that it still lingers for a portion of the population. Specifically, about 12% of people are still experiencing loss of smell or a difference in how they smell.

COVID-19 Impact on Olfactory System

The findings published in Cell on February 1, 2022, show the virus can indirectly decrease olfactory receptors. These receptors detect molecules associated with odors. The impact goes beyond initial issues with smell and interferes with other chromosomal regulation of gene expression. The research starts to help doctors better understand other neurological effects such as fogginess, headaches and depression.

“Our findings provide the first mechanistic explanation of smell loss in COVID-19 and how this may underlie long COVID-19 biology,” explains co-corresponding author Benjamin tenOever, PhD, professor at NYU Langone Health. He is quoted in a report from Becker’s Hospital Review about the findings. “The work, in addition to another study from the tenOever group, also suggests how the pandemic virus, which infects less than 1 percent of cells in the human body, can cause such severe damage in so many organs.” Consequently, the long-term impact COVID-19 can have on our nasal cavities goes far beyond common symptoms like a stuffy nose. Smell and taste are being impacted in ways that our immune system is not used to handling.

Conclusions

Understanding how COVID-19 interacts with our bodies is the first step to treating it more effectively. While the pandemic feels to us like it has been impacting our lives for an eternity, it's only been a little bit of time for scientists. Consequently, there is still more work to be done and more data to interpret.

Forbes writes, "Although this provides an explanation for the persistence of lost sense of smell, further investigations are needed to understand why recovery of olfactory neurons distorts smell and more importantly, how long-haul COVID-19 symptoms impacts brain tissues."

Researchers hope they can detect additional signals that the virus is hurting a patient’s body, such as loss of taste. The findings will help them determine new ways to treat issues earlier. As more information is discovered and findings are made public, we will update you.

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