Sneezing, tissue-grabbing and coughing — the unmistakable signs that rhinovirus season is in full swing. But while the common cold might be a nuisance, it also may have the ability to act as a barrier against other viruses, including COVID-19, experts say.
The rhinovirus, which causes the common cold, typically infects people’s upper respiratory tract — the nose, nasal passages and throat.
Common cold infections are so widespread that very few people escape infection each year. Adults typically get between two and five colds annually, according to the Canadian Centre for Occupational Health and Safety (CCOHS).
Although the rhinovirus can happen any time of the year, it tends to kick into high gear starting in September, explained Dr. Gerald Evans, an infectious disease specialist at Queen’s University in Kingston, Ont.
“September is what we call rhinovirus season, it’s when all kids go back to school or daycares,” he said.
“It’s not a particularly dangerous virus for most people, but as soon as kids return to school you see a big upswing in rhinovirus infections.”
Even though rhinoviruses are nuisances, Evans said they may help prevent the virus responsible for COVID-19 from infecting you.
“That’s something called viral interference. So a nice big rise in rhinovirus infections might be just what the doctor ordered to reduce the number of COVID cases that are sort of floating around,” he said.
How does the common cold spread?
There are more than 200 viruses that can cause colds, but the main family of viruses is the rhinoviruses, according to the CCOHS.
These viruses can live on surfaces for hours after contamination and spread mainly from person to person, Evans said.
This means that if you touch an object contaminated with a cold virus and then touch your nose or rub your eyes, you can contract a cold. When you rub your eyes, the virus can travel down the tear ducts, allowing it to reach your nose.
This is why the rhinoviruses spread so easily in daycares, Evans added.
“Rhinoviruses get spread by contact with infectious materials,” he said. “So daycare centers, of course, they have toys all over the place for kids to play with in there. If one of them has a rhinovirus and (the child) plays with the favourite toy that everybody else likes to play with, that’s how it circulates around in daycare centres and in elementary school, particularly with younger children.”
How can it interfere with other viruses?
The phenomenon of viral interference is when infection with one virus can either boost or diminish the infection and replication of a second virus, according to the U.S. Centers for Disease Control and Prevention (CDC).
Dr. Jane Heffernan, a professor at York University’s faculty of science who specializes in infectious diseases, said when someone is infected with a virus, there’s a component of their immune system that starts working called the “innate immune response.” This is the first line of defence against an invading pathogen.
“And that component could be highly active because it’s already helping fight off another virus,” she explained.
“Sometimes it’s so effective, it could stop you from getting another viral infection.”
But she warned that this is only temporary and could backfire.
“There’s always a risk that you can have another pathogen piggyback on to the first one,” potentially causing additional illnesses, Heffernan told Global News.
The concept of viral interaction is nothing new and was demonstrated in several studies prior to the arrival of COVID-19, according to a 2023 study published in the Journal of Patient-Centered Research and Reviews.
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For example, in 2009 during the H1N1 influenza pandemic (caused by a novel strain of influenza A), several studies found the rhinovirus may have played a role in deterring the spread of the sickness in places such as Sweden and Norway during the time.
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The researchers in the 2023 study said data shows that rhinovirus can interfere with the replication of influenza A and SARS-CoV-2. However, “SARS-CoV-2 does not seem to have a significant effect on rhinovirus,” the authors stated.
In another study published in 2020 in The Lancet Microbe, a team of researchers found that initial infection of rhinovirus created a strong and rapid immune response that prevented a subsequent infection with influenza or SARS-CoV-2.
This form of viral interference can happen by blocking another virus’s entry, competing for host cell resources or triggering an immune response that provides protection not only against the initial virus but also against related or different viruses, the study found.
“These results indicate that viral interference can potentially affect the course of an epidemic, and this possibility should be considered when designing interventions for seasonal influenza epidemics and the ongoing COVID-19 pandemic,” the authors said in the study.
What are the symptoms of rhinovirus?
Whether or not the common cold helps prevent another virus from entering your body, Heffernan stressed the importance of proper handwashing and staying home when you’re feeling unwell.
“A cold lasts for three to seven days and it’s most infectious when you really start to show symptoms,” she said. “You’re also infectious before you show symptoms and (for) some time after that as well.“
The symptoms tend to stay in the upper airways, meaning you’re most likely to experience a stuffy or runny nose, sneezing and a sore throat, according to Health Canada.
Heffernan cautioned that although symptoms may be mild, they can resemble those of COVID-19.
“You’ll see that maybe in the beginning some of the symptoms are similar and people might actually also confuse rhinovirus with COVID,” Heffernan said. “And because we have some pre-existing immunity, we might have mild symptoms from COVID, which could be confused as a common cold.”
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While a fever is common with COVID-19 and the flu, it is rarely a symptom of a cold.
Regardless of the illness, Heffernan said it’s crucial for individuals to ensure they stay at home, maintain physical distance from others, and take steps to prevent further spread, such as proper handwashing.
“Mostly it just comes down to getting a lot of rest, but also making sure that you’re not just laying around,” she added. “Getting up and walking around a little bit to help your immune system work.”