High levels of T-cells from a common cold could provide some protection against Covid, a study has found.
Researchers at Imperial College London found that T-cells – a type of white blood cell that helps protect the body from infection – from common cold coronaviruses may be able to provide protection against Covid.
In a study involving 52 unvaccinated people who lived with someone who had just tested positive for Covid, they discovered that those who did not catch the virus had significantly higher levels of T-cells than people who did get infected.
The study, published in Nature Communications, provides the first evidence that suggests T-cells generated by coronavirus colds help protect the body against Covid.
Professor Ajit Lalvani, senior author of the study, said: “Our study provides the clearest evidence to date that T cells induced by common cold coronaviruses play a protective role against [Covid] infection.
“These T cells provide protection by attacking proteins within the virus, rather than the spike protein on its surface.
“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.”
Researchers said no one should rely on this defence alone and people should still get vaccinated to protect themselves against the virus.
Experts warned it would be a “grave mistake” to assume that anyone who has recently had a cold is protected against Covid, as only about 10 per cent of colds were caused by coronaviruses.
But these latest findings could provide the blueprint for the production of new vaccines that would give longer-lasting immunity, including against existing and future Covid variants such as Omicron.
Study author Dr Rhia Kundu said: ”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.
Dr Simon Clarke, of the University of Reading, who was not involved in the study, said: “Although this is a relatively small study, it adds to our understanding of how our immune system fights the virus and shows that future vaccines might benefit from targeting components in addition to the spike protein.
“These data should not be over-interpreted. It seems unlikely that everyone who has died, or had a more serious infection, has never had a cold caused by a coronavirus. It could be a grave mistake to think that anyone who has recently had a cold is protected against Covid-19, as coronaviruses only account for 10-15 per cent of colds.
“Similarly, there is no measurement of how much protection the reported effect gives people and a link is only hinted at - it has not been proven conclusively.”