People who have already been infected by some common cold viruses are less likely to get COVID, according to new results from a study funded by the NIHR.
Some common colds are caused by coronaviruses, and the immune system learns to recognise them with the help of immune cells known as T cells. The new research, published in Nature Communications, shows that people with higher levels of these coronavirus-specific T cells were less likely to become infected with SARS-CoV-2, the coronavirus that causes COVID.
The study started in September 2020 when most people in the UK had no immunity against COVID. It included 52 people who lived with someone who had been diagnosed with COVID. The participants did PCR tests at the outset and 4 and 7 days later, to determine if they developed an infection - half of them developed COVID and half did not.
Researchers from the NIHR Health Protection Unit in Respiratory Infections analysed blood samples from the 52 participants to measure the levels of pre-existing T cells from previous common cold coronavirus infections that could also recognise COVID.
The researchers found that people who didn’t develop COVID had significantly higher levels of these T cells, compared to the people who did become infected. The T cells targeted internal proteins within the COVID virus, rather than the spike protein on the surface of the virus, to protect against infection.
The researchers hope their findings could provide a blueprint for a second-generation, universal vaccine that could prevent infection from current and future COVID variants, including Omicron. This is because the proteins that the T cells can recognise within the virus are less likely to change over time compared to the spike protein that is targeted by existing vaccines.
Professor Ajit Lalvani, senior author of the study and Director of the NIHR Respiratory Infections Health Protection Research Unit at Imperial, says: “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. These T cells provide protection by attacking proteins within the virus, rather than the spike protein on its surface.
"The spike protein is under intense immune pressure from vaccine-induced antibody which drives evolution of vaccine escape mutants. In contrast, the internal proteins targeted by the protective T cells we identified mutate much less. Consequently, they are highly conserved between the various SARS-CoV-2 variants, including omicron.
"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.”