Are we protected from coronavirus after the first infection? Not systematically. And only if our immune system develops antibodies against the coronavirus. According to a July 2021 study, infected adults who develop antibodies are 80% less likely to be reinfected than infected adults who do not develop antibodies. However, most infected adults produce these antibodies, so they are subsequently protected. But that doesn’t seem to be the case for kids. Australian study published March 9, 2022 in the journal Jama Open Network has just shown that most children infected with the coronavirus do not develop antibodies against the pathogen and therefore will not be immunized like adults.
Most infected children do not produce antibodies
The study analyzed blood samples from asymptomatic or mildly symptomatic children and adults with a PCR-confirmed infection that occurred between May 10 and October 28, 2020. These samples were collected at three specific time points: one week post-infection, 41 days post-infection, and 94 days post-infection. Thus, a total of 57 children (mean age 4 years) and 51 adults (median age 37 years) were followed up. Result: Only 37% of infected children developed antibodies detectable by serological test, compared to 76% of adults. And in adults, the level of antibodies increased over time, which was not the case in children.
This inability to produce antibodies would not be associated with better infection control in children because the viral load was comparable to that in adults, meaning the virus could replicate in the same way in children and adults. It could be assumed that such a low production of antibodies would be the result of a less severe illness in the child. This also applies to adults because those who develop symptoms of Covid-19 have three times more antibodies than asymptomatic adults. However, the researchers did not see a difference in this antibody level between symptomatic and asymptomatic children.