Researchers have found that children's antibodies can effectively fight out COVID-19 infection and that kids could be an underutilised source of potential antibody therapies to counteract the "ever-evolving" SARS-CoV-2 virus.

The team at Vanderbilt University Medical Center (VUMC) in the US found that children's antibodies displayed high levels of neutralisation and potency against variants of the COVID virus, even when they had not previously been exposed to or vaccinated against those variants.

"These results indicate that children's (blood) samples can play an important role in the discovery of effective SARS-CoV-2 antibody therapeutics," said the researchers led by Ivelin Georgiev from VUMC, in the study reported in the journal Cell Reports Medicine

This is important because, while monoclonal antibodies being developed initially were quite effective in neutralising SARS-CoV-2, the virus's ability to mutate rapidly has enabled it to escape from every monoclonal antibody product currently on the market.

It is crucial to find antibodies that can broadly neutralise all variants of the virus, said Georgiev, Associate Professor of Microbiology & Immunology at Vanderbilt.

Children have been thought to be unlikely sources for new antibody therapies because their immune systems are immature, and they tend to be more susceptible to severe viral illnesses including those caused by influenza, respiratory syncytial virus (RSV), and human metapneumovirus.

When it comes to SARS-CoV-2, however, children experience significantly less severe disease compared to adults. Even when adolescents have severe disease, they are hospitalised less often than adults, require shorter hospital stays, and are less likely to die from COVID-related complications.

In the study, blood samples from children aged 5 months to 18 years old were collected between July and August 2021, and divided into two groups: those with no known exposure to SARS-CoV-2 infection or vaccination, and those who had been infected or vaccinated.

The researchers found that neutralising antibodies identified in children had similar genetic features to antibodies from adults and that children use similar mechanisms for neutralising the COVID virus.

What was surprising was that the antibodies isolated from children potently neutralised SARS-CoV-2 variants that have become resistant to virtually all approved monoclonal antibody therapeutics.

Not only are children a potential source of new therapies against COVID, but deciphering their antigen-specific antibody repertoires could prove useful in improving the treatment of other infectious diseases, and the development of next-generation paediatric vaccines, the researchers said.