Dr. Richard B. Kennedy can’t help but shake his head when he sees people wearing masks with their noses uncovered.
Not only does it fly in the face of common sense, but it’s even more concerning in light of recent research showing COVID-19 has an easier time infecting people through the nasal passage than the mouth.
“My first thought is, ‘Oh come on, be smarter than that,’” said Kennedy, a Minnesota-based professor of medicine at Mayo Clinic.
His second thought is that they might as well not wear a mask at all. He estimates people are sacrificing abut 80 per cent of the mask’s protection by not covering their noses.
Clear evidence in understanding COVID-19, from how it infects people to why it causes health complications, is a constantly moving target. But it turns out many of the answers may have been right under our noses — literally.
While it’s well established that the primary way people get infected with COVID-19 is from inhaling aerosol droplets, Kennedy said there is emerging evidence it’s “a lot easier” for the virus to get a grip on our internal system when it enters through the nasal passage versus the mouth.
That’s because the nasal passage tissue is rich in cells that have a certain receptor the virus attaches to.
“There’s more cells in the upper airway in the nasal passages that have high levels of receptor expression,” Kennedy explained. “So the virus is more likely to find the cell to infect, and it’s easier for the virus to infect cells sort of in the upper airway in the nasal passages than it is down in the lungs.”
These cells are also present in the lungs, but at a lower concentration, which means the nasal passage seems to provides a more effective pathway for the virus to infect.
Robert Kozak, a clinical microbiologist at Sunnybrook Health Sciences Centre in Toronto, said a useful analogy is to think of each cell as a house and the virus as a home invader.
“If you think of a cell as a house, rather than just having one door, they’ve now got your front door, a back door, a side door, a door in the garage … perhaps some of the lung cells might only have one door instead of a couple,” Kozak said.
Not only does it seem the virus can more easily infect through the nose, but Kennedy also believes people are more likely to infect others this way.
“My guess is based on the studies that if there’s a higher concentration in the nose, that more of it’s going to come out through the nose, so a sneeze is probably got more virus than someone talking or singing or coughing,” Kennedy said.
It’s evident the nose and our sense of smell hold many answers to understanding COVID-19. It’s now clear a loss of sense of smell, known as anosmia, is one of the most common symptoms of COVID-19. Valentina Parma, chair of the Global Consortium for Chemosensory Research, said her organization’s data seems to show that anosmia is a better indicator of COVID-19 than fever.
“If we consider a sample of 100 people with COVID-19, having a fever will show up in 50 per cent of cases, but smell loss in 70 per cent of cases,” Parma said.
While loss of smell and taste are common as a cold and flu symptom, it’s usually attributed to nasal blockage from mucous buildup, Parma said. In contrast, people with COVID-19 typically report they have far less nasal blockage than they would with a cold, but an even more profound loss of sense of smell.
This is because it’s believed COVID-19 attacks the olfactory system, including the function of supporting cells in the olfactory epithelium, which is located right behind the bridge of the nose, Parma said. This could also explain why anosmia can linger for weeks or months after the virus subsides.
“Usually when we cannot smell and my nose is stuffed, then I don’t even get worried about it because I know when the cold is going to go away then my sense of smell will now function as usual,” Parma said. “But this doesn’t happen with COVID-19.”
She said the anosmia among COVID-19 patients typically lasts seven days to two weeks on average, but they are also seeing “huge variability” among patients, with some reporting lingering anosmia six months after infection.
Parma said she wants to emphasize the importance of anosmia as a positive indicator of COVID-19, especially as she expects symptoms such as runny nose and fever during fall and winter to become more common.
“My message to the general public would be you need to start paying attention to your sense of smell, especially as we’re approaching flu season,” Parma said.
For this reason, she’s an advocate of objective tests to measure sense of smell, such as sniff tests. To that end, her organization has developed an online smell and sniff test which can be completed by people by using scents in their own home, such as banana or shampoo.
Rachel Herz, a neuroscientist at Brown University and an expert in the psychology of smell, is co-developing a different smell test with plans for it to be downloadable on mobile devices.
One interesting aspect of how COVID-19 affects this area is that while it affects the olfactory nerves, which are responsible for smell, it seems to have less impact on the trigeminal nerve, which is responsible for the physical sensation people experience from certain odours, for example burning from chili peppers or soothing from menthol.
This could be very useful in better understanding neurological diseases which also include anosmia, but no loss of trigeminal sensation loss, Herz said.
“There’s potential for this to be used way beyond COVID for diseases like Parkinson’s and Alzheimer’s,” Herz said.
Another striking discovery in how COVID-19 affects the sense of smell is the presence of parosmia, which is when people experience a distorted sense of smell. Odours that were once present can suddenly become incredibly foul and Herz said more research is needed to understand this phenomenon and its connection to COVID-19.
In a sense, the pandemic has put much greater scrutiny on our sense of smell and the role it plays in overall health.
“The silver lining for me and people that do research in the sense of smell has been that there has just basically been this global awareness of the importance of the sense of smell, where generally it has always been relegated to the least important of all of our senses,” Herz said.
“And what this is bringing to the fore is recognizing that it isn’t just this trivial sensory system but, rather, it is involved with everything in our life experience.”
How do you wear your mask? Do you see others wearing masks and not covering their nose? Share your experiences.