The severity of coronavirus illness varies widely from people to people. Could the common cold be the reason why?

According to a new study, the common cold that makes you miserable can actually protect you from COVID-19 infection. A recent study at Yale University found that rhinovirus, the most frequent cause of a cold, could just jump into the body and can start the body’s antiviral defences, providing protection against coronavirus.  

This recent study is generating a lot of interest as it provides a possible explanation as to why COVID-19 can be deadly to some while it goes unnoticed in others. It is because scientists believe that infection with common cold coronaviruses can generate an immune response that resembles key pieces of the immune response generated by SARS-CoV-2, the virus that causes COVID-19

It is discovered that the presence of rhinovirus triggers the production of the antiviral agent interferon, which is part of the early immune system response to the invasion of pathogens. But scientists are still studying whether the introduction of the cold virus before infection by COVID-19 offers a similar type of protection or not.

The research also suggests that the cold that a person has had in the past may provide some protection from COVID-19. The study shows that the COVID-19-causing virus, SARS-CoV-2, induces Memory B cells that are long-lived immune cells that detect pathogens. These B cells create antibodies to destroy the pathogens by creating antibodies against them.

Memory B cells not only protect the human body from pathogens but also remembers them for the future. This is because these cells can survive for decades, and therefore could protect COVID-19 survivors from subsequent infections for a long time. This raises the possibility that previous infection with one of the milder coronaviruses could make COVID-19 less severe. 

Just a theory:

In labs all over the world lately, scientists working on COVID-19 have stumbled on an intriguing sort of finding again and again. They’ve found that blood samples from healthy people who were never exposed to the SARS-CoV-2 coronavirus contain reactive immune cells and targeted antibodies that could, perhaps, help avert COVID-19. 

Antibodies latching onto a coronavirus to neutralise it.

But this abovementioned theory is just a hypothesis that says some degree of pre-existing immunity can help protect a person from COVID-19. If by any chance, the theory is correct, it’s even possible that this immunity has saved thousands of people from the worst manifestations of this terrible disease.

The study is also the first to report that cross-reactivity of memory B cells, i.e. B cells that once attacked cold-causing coronaviruses appeared to also recognize SARS-CoV-2. Study authors believe this could mean that anyone who has been infected by a common coronavirus once, which is nearly everyone has, it is possible that the person may have some degree of pre-existing immunity to COVID-19.

During the research, the scientists studied the blood samples of people who were recovering from COVID-19, it looked like many of them had a pre-existing pool of memory B cells that could recognize SARS-CoV-2 and rapidly produce antibodies that could attack it. The study authors measured levels of memory B cells and antibodies that target specific parts of the Spike protein, which exists in all coronaviruses and is crucial for helping the viruses infect cells.


For epidemiologists, the evidence of waning immunity and cross-immunity didn’t come as a surprise. A study from 1990 showed that soldiers infected with one of the milder coronaviruses didn’t retain immunity for much longer than a year. The milder coronaviruses cases that undergo from year to year can be explained by a mix of declining immunity and cross-immunity.

The milder coronaviruses can generate similar antibodies to the ones that are generated by the coronaviruses that cause SARS and MERS. Nevertheless, infections that generate structurally similar antibodies don’t necessarily provide cross-protection in a medical way.