Coronavirus: Children have a stronger antibody response to COVID, suggests new study

Children who are 10 years or younger produce more antibodies against coronavirus infection that adults and adolescents, showed a recent study on Monday.

The study was published in the JAMA Network Open and sheds light on why children are less susceptible to severe COVID-19 than adults.

For the study, almost 32,000 antibody tests from New York City between April and August 2020 were examined. It was found that a similar number of 1,200 children and 30,000 adults showed signs of past infection.

Scientists later examined the subset of patients who tested positive - 85 children and 3,648 adults to determine the levels of immunoglobulin G (IgG) antibodies.

It is a type of neutralizing antibody that binds to the spike protein of the virus and prevents it from invading the cells.

The 32 children aged one to 10 years showed median IgG levels, almost five times higher than 127 young adults aged 19 to 24 years.

Scientists also looked at a subset of 126 positive patients aged one to 24 years, none of whom experienced severe COVID-19 to further characterize the antibody response.

In the final group, children aged one to 10 years had on average more than twice the level of IgG antibodies of adolescents aged 11 to 18 years, who in turn had more than twice the average level of young adults aged 19 to 24 years.

The findings of the study suggest that the difference in clinical manifestations of the COVID-19 in pediatric patients compared with adult patients could be partly due to age-related immune response.

As per a paper in Nature Communications published last month, it was found that children have a more active 'innate' immunity - the immune system's first line of defence which gets triggered before it raises antibodies. It involves cells such as neutrophils that patrol the body looking for infections.

Another theory claims that the children have fewer cell receptors in their respiratory tract called ACE2, which the coronavirus uses to gain entry to our cells.

One paradoxical result of the study was that the antibody levels were lowest for young adults but rose again with age, despite the fact that older people are more vulnerable.

The authors said they cannot explain this but suggested that the reason for higher hospitalisation and death rates among the elderly could be due to higher rates of comorbidities.

Obesity is one of the major risk factors for severe COVID-19. It is associated with a phenomenon called a cytokine storm, where the immune system goes into overdrive, damaging organs.