Can exposure to common cold protect against coronavirus?

The common cold can jumpstart the immune system, protecting against coronavirus infection, a new study suggests, Report informs via the Daily Mail.

Researchers from Yale University found that a virus that frequently causes colds triggers an immune response that may prevent a coronavirus from spreading in that same patient.

Results showed cold viruses may be a starting point for potential COVID treatments and offer new insight into how viruses interact.

Public health experts have noted that mask-wearing, increased handwashing, and other measures used to combat the coronavirus protected against other respiratory diseases, too.

The US had a moderate flu season in 2019-2020 and a very mild one in 2020-2021. Cold cases were also down.

Public health agencies don't measure common cold cases in the same way that they measure flu and other diseases - but stories abound of Americans who took off their masks after getting vaccinated, only to come down with their first cold in over a year.

The new study - published Tuesday in the Journal of Experimental Medicine - suggests that getting a cold might actually have some benefits - namely, protection against the coronavirus itself.

The study looked at rhinoviruses, a group of respiratory viruses that are the most frequent cause of the common cold, which be caused by a lot of other viruses, including some non-pandemic coronaviruses.

Common cold symptoms include a sore throat, sneezing, coughing, and headaches.

Symptoms are typically mild and there aren't many treatments for this virus - meaning that people rely on their immune systems to beat their colds.

That immune system response involves interferon-stimulated genes - immune system molecules that get involved early in a disease response to prevent a virus from replicating.

The Yale researchers had previously found that such an immune response from a cold can protect people against the flu, so they wanted to look for similar protection against COVID.

The team used human airway tissue grown in a lab. They infected this artificial tissue with the rhinovirus (cold virus), then with the coronavirus.

After exposure to the rhinovirus, the airway tissue activated immune system cells and completely stopped the coronavirus from spreading.

This immune system response may be adapted for treatments against COVID. But it's important to get the timing right.

The researchers also studied how the coronavirus behaves early in an infection, finding that it can spread quickly before the immune system notices.

'There appears to be a viral sweet spot at the beginning of COVID-19, during which the virus replicates exponentially before it triggers a strong defense response,' said Dr Ellen Foxman, Yale School of Medicine professor and senior author on the study, in a statement.

The cold virus immune response is thus more effective at that early-infection point. Any treatment based on this response would need to be given to a patient immediately after they become infected.

This could be tricky because it's difficult to identify COVID patients early on - patients usually do not start showing symptoms until a few days after they get sick.

If such a treatment were used too late, it could be dangerous.

At later COVID stages, high levels of those interferons - molecules that are supposed to play a role in early immune system response - can overstimulate the immune system, leading to more severe disease.

'It all depends upon the timing,' Foxman said.

Even if this immune response from the common cold isn't used to develop COVID treatments, this study still offers new insight into the complex ways that viruses interact with each other - an important area of study for future disease outbreaks.

'There are hidden interactions between viruses that we don't quite understand, and these findings are a piece of the puzzle we are just now looking at,' Foxman said.