Imperial College researchers have conducted research that indicates that people with higher amounts of T cells induced by common colds and caused by other coronaviruses are less likely to be infected by SARS-CoV-2.
The study was published this Monday (10) in the journal Nature Communications.
Previous studies had already shown that T cells from other types of coronavirus were able to recognize SARS-CoV-2. This new study, however, is the first to find evidence that these cells may play a protective role in our bodies.
In the research, there was an analysis of how these T cells act during exposure to the new coronavirus. The objective was to identify whether their presence would influence the possibility of infection.
“Being exposed to the SARS-CoV-2 virus doesn’t always result in infection, and we’ve always been interested in knowing why,” says Rhia Kundu, one of the study’s authors, in a press release. “We found that high levels of pre-existing T cells (created by the body when infected with other human coronaviruses, such as the common flu) can protect against Covid-19 infection.”
The study involved samples from 52 UK participants who lived with someone who had tested positive for Covid-19 and who therefore would have been exposed to the virus. The survey began in September 2020, when the majority of the local population had not been vaccinated or infected.
Participants took a PCR-type test as soon as the person they lived with tested positive, and a few days later, they repeated the test to determine if they had developed an infection. They also had blood samples taken, so the researchers could analyze the amount of pre-existing T cells that recognized SARS-CoV-2.
Among the 52 participants, 26 did not develop an infection. They had significantly higher levels of these T cells compared to the other 26 people who developed the infection.
T cells in these cases protected against infection because they attacked internal proteins of SARS-CoV-2, not the spike protein on the surface of the virus.
The researchers say the discovery could lead to the development of new vaccines that provoke an immune response directed at these internal proteins. Protection from this type of vaccine could be longer lasting, as T-cell immune responses persist longer than antibody responses.
“The internal proteins that are targeted by the protective T cells we identified undergo far fewer mutations. [do que a proteína spike]. Consequently, they are highly present among the various variants of SARS-CoV-2, including Ômicron”, says Professor Ajit Lalvani, co-author of the research. “New vaccines that include these internal proteins would therefore induce T cell responses, which may protect against current and future variants,” he adds.
The scientists note that there are some limitations to the study, as it analyzed a relatively small number of people and that 88% of them were white and European — meaning that the results obtained may not be applicable to other groups.
Rhia Kundu also emphasizes that one should not rely solely on the possibility of an immune response from pre-existing T cells as a form of protection. “The best way to protect yourself against Covid-19 is to be fully immunized, including the booster dose”, he stresses.
Reference: CNN Brasil
