Research: some people have antibodies to coronavirus, although they did not get sick

In an experiment involving 300 people, British researchers found that approximately 5% of adults have antibodies to coronavirus. Scientists believe that they appeared when infected with a “related virus”.

A small fraction of the population has antibodies that respond to the coronavirus, even though they have not been infected, a new study found. Scientists believe that these antibodies emerged during infection with related viruses.

Research proves that some people may have some degree of pre-existing immunity to the coronavirus. However, while these findings may explain some of the pandemic’s tendencies (for example, children are less vulnerable to severe disease), it is still unclear how protective this borrowed immunity might be.

The study, published in the journal Science, analyzed blood samples collected from adults and children in the UK prior to the outbreak of the pandemic in December 2019. Scientists also studied analyzes of people in the early stages of the pandemic who tested negative for coronavirus. These samples were matched to people who had confirmed coronavirus.

They found antibodies in some uninfected patients, including those who recently had a common cold. The researchers found that they nevertheless reacted to SARS-CoV-2. “Our results from multiple, independent analyzes showed the presence of pre-existing antibodies that recognize SARS-CoV-2 in uninfected patients,” the researchers write.

The antibodies found in uninfected people were different from those found in patients with coronavirus. These were IgG antibodies. They found them only in a small number of adults – in 302 samples they were found only in 5.26% of cases. In children, this rate was higher – researchers found antibodies in 21 of 48 samples (44%) collected from children aged 1 to 16 years.