THE ESSENTIAL
- The study focused on the analysis of viral load and antibody levels in children and adults
- At comparable viral load, the level of antibodies was much lower in children
- This could indicate a higher risk of reinfection for younger people
If children are more immune to severe forms of Covid-19, they may be at a higher risk of reinfection than adults. This is the conclusion of a study published on March 9 in JAMA Network Open which suggests that children’s initial immune response is more robust, allowing them to clear infection more quickly. But this response producing fewer antibodies and these being very important to guard against reinfection, questions exist as to the protection of the youngest against future infections.
Comparable viral loads but big differences in antibody levels
The study involved 57 children with a median age of 4 years and 51 adults with a median age of 37 years, all of whom tested positive for first variants of SARS-CoV-2 between May and October 2020. All of these participants had mild symptoms (headache and fever), or even were asymptomatic. From samples in the nose and throat, the level of viral RNA was measured for each as well as the presence of antibodies from blood samples. Result, very comparable viral loads between children and adults but on the other hand, a big difference in the presence of antibodies against the coronavirus in the blood, only 37% of children having produced them against 76% of adults.
Less adaptive immune response in children
The explanation could come from the fact that children have a stronger innate immune response – the first line of defense against pathogens – than adults and that their body quickly eliminates the virus in such a way that it does not leave traces. to trigger the adaptive response that produces the antibodies. By the way, the Australian team that conducted this study also measured the levels of immune cells in the blood and found fewer memory B and T lymphocytes (those that produce antibodies) in children than in adults. According to Betsy Herold, a New York infectious disease physician, “this suggests that children develop less of an adaptive immune response, one that generates immune memory.”
This would put children at greater risk of re-infection, although, as Betsy Herold points out, “we don’t yet have the data to draw that conclusion and if we do have that if children aren’t as protected from re-infection they are still at a lower risk of complications from the initial infection anyway“.