The common cold may provide immunity against COVID-19

Colds that you have had in the past may provide you with protection from COVID-19, according to a new study by infectious disease experts at the University of Rochester Medical Center. The research also suggests that once you gain immunity to COVID-19, it will last a long time – possibly even a lifetime.

Following an initial infection, the body produces memory B cells to create antibodies that remember pathogens and destroy them in the case of re-infection. These cells, which can survive for decades, are ready to spring into action the next time a particular pathogen enters the body. 

The current study is the first to show that SARS-CoV-2 induces the formation of memory B cells. Theoretically, these cells will provide immunity to anyone who has had COVID-19, clearing up a future infection before it even begins. The experts say that further research is needed to investigate.

The study is also the first to find that memory B cells which once attacked cold-causing coronaviruses appear to also recognize SARS-CoV-2. This cross-reactivity of memory B cells could mean that anyone who has been infected by a common coronavirus – which is nearly everyone – may have some degree of pre-existing immunity to COVID-19, explained the researchers.

Study lead author Dr. Mark Sangster is a research professor of Microbiology and Immunology at URMC.

“When we looked at blood samples from 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,” said Dr. Sangster.

The experts compared blood samples from 26 people who were recovering from mild to moderate COVID-19 to blood samples from 21 healthy volunteers, whose blood was collected before they could have been exposed to COVID-19. Using these samples, the researchers measured levels of memory B cells and antibodies that target specific parts of the spike protein that exists in all coronaviruses to help them gain entry into human cells. 

While the spike protein looks and behaves a little differently in each coronavirus, one of its components – the S2 subunit – is basically consistent across all of the viruses. Memory B cells cannot distinguish between the spike S2 subunits of various coronaviruses. 

The study indicates that Memory B cells attack without discrimination when it comes to betacoronaviruses, a subclass that includes two cold-causing viruses, SARS, MERS, and SARS-CoV-2. The research does not yet reveal the extent of the immunity that may be provided by cross-reactive memory B cells or how this protection may affect patient outcomes.

“That’s next,” said Dr. David Topham. “Now we need to see if having this pool of pre-existing memory B cells correlates with milder symptoms and shorter disease course – or if it helps boost the effectiveness of COVID-19 vaccines.”

The study is published by the American Society for Microbiology in the journal mBio.

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By Chrissy Sexton, Earth.com Staff Writer