COVID-19's symptoms are often confused, but this is a condition that can last for a long time. According to a new study, one patient has yet to recover their sense of smell after infection.
Dr. Paolo Boscolo-Rizzo told Medical News Today: "It's a good thing."
Both smell and taste refer to the emotional and affective level of [an] experience more than other senses; they are impossible to communicate through social networks such as ideas, images, and music; rather, sharing them requires coexistence. Thus, loss of the sense of smell and taste negatively impacts quality of life, as it deprives those affected of several everyday pleasures and social bonds.
Dr. Boscolo-Rizzo is the co-author of an editorial accompanying the publication of a new meta-analysis (a study of other studies) examining just how long a loss will last after an acute SARS-CoV-2 infection.
The research was published in The BMJ.
The recovery process may be sluggish.
The World Health Organization has so far reported over 572 million cases since the outbreak began, and many people have been infected more than once. According to the study, 40% to 50% of people who have had COVID-19 experience a loss of smell and taste.
In 18 investigations encompassing the experiences of 3,699 patients, the researchers looked at smell and taste loss.
After the SARS-CoV-2 infection, the authors estimate that about 5% of adult COVID-19 patients develop long-term changes to their sense of smell or taste, with 15 million and 12 million adults experiencing long-term smell and taste deficiencies.
Women were less likely than men to recover their sense of smell and taste, and patients who experienced more severe smell loss and nasal congestion were also less likely to recover their sense of smell right away.
Nevertheless, not all statistics painted a grim picture.
Professor Claire Hopkins, a co-author of the study, told MNT that it's good news for those who are waiting for their senses of smell and taste to return.
The majority of patients have recovered following COVID smell loss in six months, according to this research. This is very helpful for patients in the first weeks or months after infection.
According to the study's analysis, 96 percent of individuals reported feeling refreshed or improved after six months.
Prof. Hopkins adds that two-year follow-up data that haven't been published suggest that there's a long-term rebound.
The relationship between smell and taste
According to Dr. Simon Gane, an ear, nose, and throat surgeon who was not involved in the study or the editorial, the majority of what we normally refer to as taste is actually smell.
Salt, sweet, bitter, sour, and umami are the only things we can detect in the nose, according to the author. Everything else is detected in the nose when smell molecules go up from the back of the mouth to the back of the nose.
People will often describe their sense of smell and taste as they only lose their sense of smell. Dr. Simon Gane
COVID-19 has also been noted by Gane, although not as often, and usually not permanently.
Prof. Hopkins claims that a small number of patients also have a true taste loss with sensitive smell tests, although this is typically uncommon.
COVID-19's effect on the sense of smell
Experts believe that SARS-CoV-2, the virus that causes COVID-19, can affect the nasal, or olfactory, neuroepithelium.
Dr. Boscolo-Rizzo explains:
The olfactory neuroepithelium is located on the roof of nasal cavities and is composed of olfactory sensory neurons and supporting cells that protect the fragile sensory cells.
According to him, the olfactory sensory neurons give rise to an electrical signal that, through many stations, will reach the brain's olfactory cortex, returning a conscious perception of smells.
Prof. Hopkins explained that the nose's cilia, or hair-like projections, are covered with receptors that detect odors.
With COVID-19, Dr. Boscolo-Rizzo explains that the neuroepithelium is likely to be involved in the loss of taste and smell.
The olfactory neuroepithelium's supporting cells are extremely rich in ACE2 receptors, making them the ideal host for the SARS-CoV-2 virus. On the contrary, the olfactory sensory neurons are devoid of the ACE2 receptor.
Aber damage to the support cells, according to the author, also affects neurons. Substances released from the support cells infected by the virus result in a decrease in the number of olfactory receptors in the olfactory sensory neurons, causing anosmia, the loss of the sense of smell.
Smell is a piece of the brain projected onto the outside world, according to Dr. Boscolo-Rizzo: The olfactory neuroepithelium is used to being damaged.
The olfactory neuroepithelium has an extraordinary and unique characteristic for a nervous tissue: the ability to regenerate. So, the recovery of the sense of smell, even if it can take a long time, is possible. Dr. Paolo Boscolo-Rizzo
An exciting frontier for olfactory science
Dr. Boscolo-Rizzo noted that the epidemic has highlighted the importance of maintaining healthy senses of smell and taste, which were often forgotten and dismissed as irrelevant.
Prof. Hopkins argues that research on olfactory disorders has been neglected throughout history, both by researchers and funding bodies. There is [a] need, but also [an] opportunity, to increase research in this area. There are currently many trials underway throughout the world that may lead to better outcomes for our patients.
He said that many research organizations are testing new therapies in clinical trials that may be useful in treating both post-COVID-19 anosmia and other forms of post-viral anosmia.
He stressed that those who govern our destiny must be aware of the necessity of involving in both basic and clinical chemosensory research. We hope this is the positive side of the devastating experience experienced during this epidemic.