Cross-reactive memory T cells associate with protection against SARS-CoV-2 infection in COVID-19 contacts (10 January 2022)

Summary

People who have already been infected by some common cold viruses are less likely to get COVID, according to new results from a study by Kundu et al. funded by the NIHR.

Content

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.