How the common cold may help protect against Covid-19

People who have fought off common colds may have a lower risk of catching Covid-19, according to a newly published study.

The research findings, outlined in a paper in Nature Communications journal, help to “explain why some people never get infected” with Covid, and why older people are “more susceptible” than children, who tend to pick up colds more frequently, said The Telegraph.

In the small-scale study, scientists from Imperial College London (ICL) tested blood taken from 52 people in September 2020 – before Covid vaccines were rolled out – who were living with others who had just tested positive for the coronavirus. A total of 26 went on to get Covid during the 28-day study period.

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In a bid to determine why the other half of the group escaped infection, the researchers looked at “a crucial part of the body’s immune system – T-cells”, said the BBC.

Some of these T-cells “kill any cells infected by a specific threat”, such as a cold virus, the broadcaster explained. And following a cold infection, some “remain in the body as a memory bank, ready to mount a defence against future attacks” by the virus.

The researchers found that the 26 test subjects who did not contract Covid had “significantly higher levels” of “pre-existing T-cells induced by previous common cold coronavirus infections that also cross-recognise proteins” of Sars-CoV-2, the virus that causes Covid-19, according to the ICL website.

‘Blueprint’ for future vaccines

The findings suggest that these protective T-cells may be present in “a good proportion of the population”, study co-author Professor Ajit Lalvani told The Telegraph.

“It explains the good outcomes or resistance to infection for some people,” added Lalvani, director of the NIHR Respiratory Infections Health Protection Research Unit at Imperial.

The researchers believe that the “important discovery” may provide a “blueprint” for the production of a new universal vaccine that “could prevent infection from current and future Sars-CoV-2 variants, including Omicron”, said the ICL website.

Dr Rhia Kundu, first author of the study, stressed that “no one should rely on this alone”, adding: “The best way to protect yourself against Covid-19 is to be fully vaccinated, including getting your booster dose.”

The team and other scientists pointed out that not all colds are coronaviruses. Dr Simon Clarke, of the University of Reading, who was not involved in the study, said: “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% of colds.”

Experts said that “other variables – such as ventilation and how infectious their household contact was – would have an impact” on whether people caught Covid, too, the BBC reported.

All the same, said study co-author Lalvani, “learning from what the body does right could help inform the design of new vaccines”.

Current vaccines target spike proteins that sit on the outside of the Covid virus, but those spike proteins can change with new variants.

“In contrast, the internal proteins targeted by the protective T-cells we identified mutate much less,” Lalvani explained. So new vaccines that include these internal proteins would “induce broadly protective T-cell responses that should protect against current and future Sars-CoV-2 variants.”