British scientists have found how common colds may help protect some people, especially children, against COVID-19 infection.
There has been speculation for some time that colds caused by coronaviruses might provide protection – and now a scientific study at the Francis Crick Institute has found pre-existing protective antibodies in some people.
The antibodies were notably strong in children, according to a report published in Science.
The finding was a chance discovery as the scientists sought to develop new assays for COVID-19.
These showed that some people had antibodies that recognised the virus – even though they were not thought to have had COVID-19.
This was further tested on 300 samples of blood collected before the pandemic. About 5% of adults had antibodies that reacted to SARS-CoV-2. Prevalence was much higher among children aged between six and 16, they report.
Researcher Kevin Ng said: "Our results show that children are much more likely to have these cross-reactive antibodies than adults. More research is needed to understand why this is, but it could be down to children being more regularly exposed to other coronaviruses.
"These higher levels we observed in children could also help explain why they are less likely to become severely ill with COVID-19. There is no evidence yet, however, that these antibodies prevent SARS-CoV-2 infection or spread."
Fellow researcher George Kassiotis said: "The spike of this coronavirus is made of two parts or subunits, performing different jobs. The S1 subunit allows the virus to latch onto cells and is relatively diverse among coronaviruses, whereas the S2 subunit lets the virus into cells and is more similar among these viruses. Our work shows that the S2 subunit is sufficiently similar between common cold coronaviruses and SARS-CoV-2 for some antibodies to work against both.
"It was previously thought that only antibodies to the S1 could block infection, but there is now good evidence that some antibodies to S2 can be just as effective. This is exciting as understanding the basis for this activity could lead to vaccines that work against a range of coronaviruses, including the common cold strains, as well as SARS-CoV-2 and any future pandemic strains.”
Kevin W. Ng et al. Preexisting and de novo humoral immunity to SARS-CoV-2 in humans. Science 8 November 2020
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