The common cold may give you immunity from COVID-19 for a lifetime

A new study says that seasonal colds you've had in the past could protect you from COVID-19, maybe even for a lifetime. Read on to know more.

सर्दी-जुकाम और एलर्जी में आयुर्वेदिक सिरप फायदेमंद है।

Almost everyone in this world has suffered from the common cold at some point of life in their lives. It is a debilitating condition, but not fatal, which can cause clogged nose, loss of sense of smell and taste and other symptoms that bear resemblance to symptoms of COVID-19. Seasonal colds are by all accounts no fun, but new research suggests the colds you've had in the past may provide some protection from COVID-19. The study, authored by infectious disease experts at the University of Rochester Medical Center, also suggests that immunity to COVID-19 is likely to last a long time -- maybe even a lifetime. The study, published in mBio, is the first to show that the COVID-19-causing virus, SARS-CoV-2, induces memory B cells, long-lived immune cells that detect pathogens, create antibodies to destroy them and remember them for the future. The next time that pathogen tries to enter the body, those memory B cells can hop into action even faster to clear the infection before it starts.

Immunity may last for even a lifetime

Because memory B cells can survive for decades, they could protect COVID-19 survivors from subsequent infections for a long time, but further research will have to bear that out. The study is also the first to report cross-reactivity of memory B cells -- meaning 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 -- which is nearly everyone -- may have some degree of pre-existing immunity to COVID-19.

B cells recognize part of spike protein common to all coronaviruses

When researchers 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. Sangster's findings are based on a comparison of blood samples from 26 people who were recovering from mild to moderate COVID-19 and 21 healthy donors whose samples were collected six to 10 years ago -- long before they could have been exposed to COVID-19. From those samples, 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.

Pre-existing memory B cells means milder infection

The Spike protein looks and acts a little different in each coronavirus, but one of its components, the S2 subunit, stays pretty much the same across all of the viruses. Memory B cells can't tell the difference between the Spike S2 subunits of the different coronaviruses, and attack indiscriminately. At least, the study found that was true for betacoronaviruses, a subclass that includes two cold-causing viruses as well as SARS, MERS and SARS-CoV-2. What this study doesn't show is the level of protection provided by cross-reactive memory B cells and how it impacts patient outcomes. Researchers now hope to conduct further studies 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.

(With inputs from IANS)