New Delhi: When the coronavirus outbreak initially began, one of the most common questions and concerns medical professionals had were that there was so little known about the virus. As we gained more information about the virus, it has come in handy in the production and development of vaccine candidates, and treatments for severe and mild COVID-19. However, it seems that our bodies are smarter, and have already learnt to recognise the COVID-19 infection.

The immune system’s memory helper, known as T cells, which recognise the common cold virus and help the body to fight it, can also identify some part of the novel coronavirus, a study has found. These findings may also explain why some people have milder COVID-19 infection than others. 

The research was published in the journal Science. The researchers found that the T cells keep track of the viruses they have encountered before, which helps the immune system in recognising and fighting pathogens. 

Researchers defined the exact parts of the virus that are responsible for the cross-reactive T cell response. On analysing, they found that individuals who have never been exposed to SARS-CoV-2 can produce a range of memory T cells that are equally reactive against novel coronavirus and four types of common cold coronaviruses.

Based on these findings, the scientists concluded that fighting off a common cold coronavirus could teach the T cells to recognise some parts of SARS-CoV-2. They believe that this process provides evidence for the hypothesis that common cold viruses can, in fact, induce cross-reactive T cell memory against SARS-CoV-2.

Scientists, however, have warned that it may be too soon to say if such existing memory affects how the novel coronavirus affects the body. 

“We have now proven that, in some people, pre-existing T cell memory against common cold coronaviruses can cross-recognise SARS-CoV-2, down to the exact molecular structures,” said Daniela Weiskopf, a co-author of the study from LJI. “This could help explain why some people show milder symptoms of the disease while others get severely sick,” Weiskopf said, news agency PTI reported. 

Alessandro Sette, another co-author of the study also said that the reactivity of the immune system may lead to different degrees of protection from the virus. 

“Having a strong T cell response, or a better T cell response may give you the opportunity to mount a much quicker and stronger response,” Sette said.

Another study by Sette and his team had shown that about 40 to 60 per cent people who were never exposed to the novel coronavirus had T cells that reacted to the virus. The study said that the immune systems of these people recognised bits of the coronavirus, that it had never encountered before. Similar findings were also reported from the Netherlands, Germany, Singapore, and the UK. 

These findings can enhance the potential to take advantage of this cross-reactivity, and could further enhance vaccine potency.