Having high levels of these cells, induced by colds, means we are less likely to catch Covid-19, Miriam Stoppard says, and could lead to a new universal vaccine
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Science works in mysterious ways. Who’d have thought the common cold could protect against Covid-19? Well, it can. Many common cold viruses are coronaviruses, and people with higher levels of T cells from suffering cold coronaviruses are less likely to become infected with Covid.
We know T cells are a crucial tool in our immune system toolbox. And it turns out the presence of these particular T cells at the time of exposure to Covid influences whether you get it.
Dr Rhia Kundu, first author of the study from Imperial College’s National Heart and Lung Institute, says: “Being exposed to the SARS-CoV-2 virus doesn’t always result in infection, and we’ve been keen to understand why.
“We found that high levels of pre-existing T cells, created by the body when infected with other human coronaviruses like the common cold, can protect against Covid-19 infection.
“While this is an important discovery, it is only one form of protection, and I would stress that no one should rely on this alone.
“Instead, the best way to protect yourself is to be fully vaccinated.”
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Blood samples from 52 people were taken within one to six days of exposure to the virus so researchers could analyze the levels of pre-existing T cells induced by previous common cold coronavirus infections that also cross-recognize proteins of Covid.
In the 26 people who didn’t get Covid there were significantly higher levels of these cross-reactive T cells compared to the 26 people who did become infected.
Importantly, these T cells targeted the virus itself, and not just its spike proteins. “Our study provides the clearest evidence to date that T cells induced by common cold coronaviruses play a protective role against SARS-CoV-2 infection,” said Professor Ajit Lalvani, director of the NIHR Respiratory Infections Health Protection Research Unit at Imperial College London.
Current vaccines don’t induce an immune response to the virus itself so these T cells are reacting to a new vaccine target that could provide long-lasting protection.
T cells persist longer than antibodies.
Prof Lalvani, senior author of the study, says: “Our study provides the clearest evidence to date that T cells induced by common cold coronaviruses play a protective role.
“These T cells provide protection by attacking proteins within the virus, rather than the spike protein.
“New vaccines that include these conserved, internal proteins would therefore induce broadly protective
T cell responses that should protect against current and future SARS-CoV-2 variants.”
In other words a universal vaccination that could prevent infection from future Covid variants. Phew!