The coronaviruses are responsible for the respiratory disease COVID-19.
Since its discovery in late 2019, the coronavirus has led to more than 6.45 million deaths worldwide and more than 1 million deaths in the United States.
COVID-19 can lead to severe or life threatening illness, especially in older adults, people who are not vaccinated, and people with weakened immune systems. Most people with COVID-19 develop mild symptoms.
Loss of smell and taste are the most reported symptoms. Other common symptoms of COVID-19 include:
- fever or chills
- The breath was very thin.
- The muscles are sore.
- There are headaches.
- sore throat.
- stuffy nose or runny nose
- nausea or vomiting
- There is a lot of diarrhea.
People with certain genes may lose taste or smell more often. Scientists are looking at this association. We know a lot about the link.
Loss of smell and loss of taste are commonly reported COVID-19 symptoms. Researchers are continuing to examine why some people with COVID-19 develop these symptoms while others don’t. Recent evidence suggests genetics may play a role.
Among 32,142 people with COVID-19 in a 2021 review of studies, 38.2% of them developed loss of smell while 36.6% developed loss of taste.
Researchers found that certain location variants of the UGT2A1 and UGT2A2 genes expressed in the olfactory epithelium were associated with COVID-19-related loss of smell. Your olfactory epithelium is a thin layer of tissue along the roof of your nose that helps you smell.
These genes play a role in metabolizing substances that make you smell. It is not clear how and why these genes influence smell loss.
Several possible reasons people with COVID-19 develop loss of smell have been hypothesized, but the exact cause isn’t clear. Possible mechanisms theorized to contribute include:
- There is obstruction of the airway.
- Damage to olfactory cells.
- The olfactory centers in the brain have been damaged.
- The cells supporting olfactory cells are malfunctioning.
- The olfactory cells have inflammation-related functions.
Evidence shows that the coronaviruses enters and accumulates in olfactory support cells through angiotensin converting enzyme 2 and transmembrane protease serine 2. Your ability to smell can be impaired by the breakdown of these cells.
- Women reported losing smell or taste more often than men.
- “The average age of people who reported losing their smell or taste was 41 years, compared with 45 years for people who didn’t experience these symptoms.”
- people of East Asian descent and African Americans were significantly less likely to develop these symptoms than people of European descent
Within a couple of months most people regain their sense of smell or taste. Some people have effects that can last for a year or more.
“Your doctor may recommend olfactory training if your smell doesn’t return.”
Steroids and high doses of omega-3 fatty acids may be recommended by some doctors. These are effective for treating smell loss from non-viral causes.
Visit your doctor if you or your child have lingering symptoms that persist about 4 weeks or longer after you develop COVID-19.
Your doctor can suggest tests that can help identify the root cause of your symptoms.
“Symptoms of COVID-19 include loss of taste and smell. Some people develop these symptoms and others don’t, so researchers are trying to understand why. Evidence suggests genetics may contribute.”
In particular, researchers have identified UGT2A1 and UGT2A2 as genes linked to COVID-19-related smell loss. More research is needed to understand exactly what role these genes play.