The small-scale study conducted by Dr Rhia Kundu and her colleagues at Imperial College London looked at 52 people who were living with someone who had recently contracted COVID-19.
The authors of the study immediately note certain limits to their results due to the small number of participants only of European origin, but they believe that their data nevertheless provide a first indication of a protective role of these T lymphocytes against disease.
Other studies have shown that T cells developed during infection with other coronaviruses can recognize SARS-CoV-2, but the new study examines for the first time how the presence of these cells associated with the immune response at the time of exposure to SARS-CoV-2 affects a person’s possibility of infection.
These results provide a plan to create a second-generation universal vaccine that could prevent infection with current and future variants of SARS-CoV-2, including Omicron, explain in a press release the researchers, whose work details are published in the journal Nature CommunicationsHave (New window)Have (in English)
” Exposure to SARS-CoV-2 does not always lead to infection, and we sought to understand why. We have found that high levels of pre-existing T cells, created by the body during infection with other human coronaviruses like the common cold, can protect against infection with COVID. “
Vaccination remains necessary
Dr. Kundu believes that it is still important to be vaccinated against COVID-19.
The best way to protect yourself against COVID-19 is to be fully immunized, including getting your booster dose, insists the researcher.
The study began in September 2020, when most people in the UK had not been infected or vaccinated against SARS-CoV-2. The participants lived with a person whose infection with SARS-CoV-2 had been confirmed by a PCR test. The fifty or so participants had therefore been exposed to the virus. They underwent PCR tests initially and then 4 and 7 days later to determine if they had developed an infection.
Blood samples from the 52 participants were taken between one and six days after exposure to the virus. This allowed researchers to analyze the levels of pre-existing T cells induced by previous cold coronavirus infections, which also recognize proteins from the SARS-CoV-2 virus., reports the press release.
The results show that the 26 volunteers who were not infected had significantly higher levels of T cells than the 26 people who were infected. These T cells targeted the internal proteins of the SARS-CoV-2 virus, rather than the S protein (for spicule, which forms the tips at the end of the coronavirus crown), to protect against infection.
A vaccine that targets internal proteins
The researchers believe that alongside current vaccines that target S proteins, vaccines that attack internal proteins could be a new vaccine target. These new vaccines would, they say, offer lasting protection, because the T cell response persists longer than the antibody responses, which fade a few months after vaccination.
Our study provides the clearest evidence to date that cold coronavirus-induced T cells play a protective role against SARS-CoV-2 infection. These T cells provide protection by attacking proteins inside the virus, rather than the spike protein on its surface., concludes Professor Ajit Lalvani, who took part in the work.
The S protein is under intense immune pressure from the antibodies induced by the vaccine, which causes the evolution of variants. In contrast, the internal proteins targeted by the protective T cells that we have identified mutate much less. Therefore, they are highly conserved between different variants of SARS-CoV-2, including Omicron, concludes the professor.