The article by scientists from the Murdoch Children’s Research Institute (Australia) has not yet been peer-reviewed and has been published on the medrxiv preprint site. The study compared antibody titers in 57 children and 51 adults with mild or asymptomatic COVID-19. The infection was confirmed by PCR testing, after which specialists took blood samples from all participants for 41 days.
All adult patients showed a significant increase in neutralizing antibodies from the moment of the acute phase of the disease to complete recovery. However, in children, the dynamics of the increase in antibody titer was lower. The results were validated using four different test systems.
Antibodies were developed in 76% of adult participants, the immune response was absent mainly in asymptomatic carriers. In the group of children, antibodies were developed only in 37% of the participants, and their presence or absence was not with the transferred form of infection. It is noteworthy that seronegative children did not develop antibodies even on the 94th day after the onset of symptoms. They also lacked a cellular immune response, while asymptomatic adults did.
According to scientists, this study was carried out last year before the spread of the delta variant of coronavirus, so at the moment it is impossible to say whether these features of the immune response in children are at risk of recurrence.
“We have to investigate whether the same happens when the delta variant is infected,” the study authors said.