Common cold antibodies developed in past can help fight Covid-19: Study

New research suggests that people who have had a bout of seasonal flu or common cold may have developed a certain kind of protection against coronavirus.

The researchers further claimed that the immunity may last for a long time, even a lifetime, as per the study published in the journal mBio.

The researchers stated that pathogens stimulate memory B cells, long-lived immune cells that detect pathogens and build antibodies to kill them. They even remember the pathogens for the future.

According to the researchers from the University of Rochester Medical Center (URMC) in the US, memory B cells get automatically activated if the pathogen tries to enter the body.

Memory B cells can be activated for decades, they could protect Covid-19 survivors from subsequent infections for a long time. However, researchers need further confirmation on this.

The study further explained the cross-reactivity of memory B cells. This means that B cells that once protected the body from cold-causing coronaviruses seem to also recognize SARS-CoV-2.

The researchers believe 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.

Study lead author Mark Sangster, a research professor at URMC said in a statement: "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.”

Researchers compared 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.

The researchers then measured levels of memory B cells and antibodies that target specific parts of the Spike protein, which are present in all coronaviruses and helps the virus attach and proliferate.

Researchers maintained that the spike protein may act differently in different types of coronaviruses, however, 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, the researchers said.

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