Got Common Cold In The Past? You Might Have Some Immunity Against COVID-19, Says New Study

A new study on COVID-19 suggests that immunity developed against the disease can possibly last a lifetime. It further points out that a bout of seasonal or common cold in the past can help attain some of this immunity.

Published in the journal mBio, the new study has been conducted by researchers from the University of Rochester Medical Center (URMC) in the US. The research highlights that SARS-CoV-2, the virus that causes COVID-19, is able to induce memory B cells in the human body.

These memory B cells are long-lived immune cells that are able to detect pathogens and create antibodies to destroy them for a long time in the human body. Once developed, these memory B cells can act even faster the next time the pathogen tries to enter the body.

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Memory B cells can survive for decades and hence could act as a possible protection against COVID-19 in survivors from subsequent infections for a long time. Further research, however, is needed to confirm this.

The cross-connection

The study is also the first of its kind to map the cross-reactivity of memory B cells. Interestingly enough, it found that B cells that were once produced in the body to attack cold-causing coronaviruses also seemingly recognised SARS-CoV-2.

These findings led the researchers to believe that those who have been infected by a common coronavirus, i.e. nearly everyone, might have some degree of pre-existing immunity to Covid-19.

"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 recognise SARS-CoV-2 and rapidly produce antibodies that could attack it,¡± said Mark Sangster, a research professor at URMC and the lead author of the study.

The first of its kind research

(Representative Image: Reuters)

To get these results, the scientists compared blood samples from 26 people recovering from mild to moderate Covid-19 with those from 21 samples from healthy donors collected six to 10 years ago. The old blood samples were taken to ensure that the healthy individuals could not have been exposed to Covid-19.

From the blood samples, the researchers measured levels of memory B cells and antibodies. These target specific parts of the Spike protein, a common constituent in all coronaviruses and crucial for the viruses to infect cells. An S2 subunit of this Spike protein was found to be pretty much the same across all of the viruses.

The scientists found that the memory B cells are unable to differentiate between the Spike S2 subunits of different coronaviruses. These cells thus attack any and every type of coronavirus indiscriminately, including SARS, MERS and SARS-CoV-2.

The study, however, did not map the exact level of cross-reactive memory B cells needed to provide adequate protection against Covid-19. Further research is needed to know that.

(With inputs from PTI)