Exposure to SARS, other coronaviruses may make some people immune to COVID-19: Report

Representative Image (AP Photo/Mahesh Kumar A.)

A study by Singapore-based researchers have found that some individuals may have developed immunity to the novel coronavirus – scientific name SARS-CoV-2 – due to exposure to other coronaviruses.

As per the study, published in Nature journal on July 15,  a few people may have developed an immunity to COVID-19 even without being exposed to it due to having been previously infected by other coronaviruses, as per a Hindustan Times report.

According to the study, some individuals have T-cells,  the type of white blood cells that recognise the virus’ two proteins – structural or nucleocapsid proteins and non-structural viral proteins (NSP). T-cells typically detect viruses/infections in the immune system.

“We characterised Sars-CoV-2 specific T-cells in COVID-19 and SARS (the 2003 outbreak) convalescents and uninfected healthy individuals,” Dr Antonio Bertolleti, study co-author and professor of emerging infectious diseases at Duke-Nus Medical School in Singapore told the paper.

Dr Bertolleti added that individuals who recovered from COVID-19 possessed T-cells structural proteins more efficiently than NSPs and had also been infected with SARS – which they also recovered from, thus suggesting cross-reactive cellular immunity.

The development is significant as it may give scientists more clues in building a vaccine against COVID-19, as those with immunity generate neutralising antibodies. After reviewing the paper, drug developer Derek Lowe said T-cell immunity may drive vaccine development against COVID-19, it added.

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The study found that over 50 percent of COVID-19 negative individuals demonstrate T-cells equipped to detect SARS-CoV-2 and these cells “recognised more frequently sequences of non-structural proteins found only in animal coronaviruses.”

Thus, a large part of the population possesses Sars-Cov2-specific T cells, likely induced by other coronaviruses. “One possible implication of our findings is that many subjects might have a level of progress T-cell reactivity that might partially protect them,” he added.

Experts however are not surprised as an average of 20 percent common cold cases are due to coronaviruses, which means they are already widespread among humans. For reference, SARS-CoV-2 shares 80 percent sequence identity with SARS and 50 percent with other coronaviruses, Shahid Jameel, virologist and CEO of Wellcome Trust/DBT India Alliance noted.

Notably, India was largely spared from the SARS outbreak in 2003, so how much of the population could have immunity is debatable.

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