Background: Data on seroconversion rates after SARS-CoV-2 infection in young children (<6 years) is scarce. The present study compares seroconversion rates between young children and adults and identifies associated factors.
Methods: The COALA study ("Corona-outbreak-related examinations in daycare centers") investigated transmission dynamics of SARS-CoV-2 in daycare centers and associated households (10/2020-06/2021). 114 individuals tested positive for SARS-CoV-2 through PCR either prior to the study period by health authorities or in PCR testing during the study period. Two capillary blood samples were obtained within five weeks consecutively and tested for SARS-CoV-2 IgG-antibodies (second sampling depending on positive PCR). Results from 91 participants (38 young children 1-6 years, 53 adults) were included in the analyses.
Results: Seroconversion rate in young children is significantly higher than in adults (97.4% versus 66%). High viral load and longer time interval between the probable date of infection and antibody testing are associated with seroconversion.
Conclusions: Our findings depict substantial development of specific antibodies in young children after SARS-CoV-2 infection. This may provide temporary protection from re-infection for young children or severe disease for this age group.
When fighting an infectious disease, the immune system often produces antibodies. These proteins circulate in the blood, where they help to clear the infection and generally remain present for several months after recovery. Little is known about how often children younger than 6 years develop antibodies after SARS-CoV-2 infection. The aim of our study was to compare antibody development of young children and adults. We examined blood samples from young children and adults after SARS-CoV-2 outbreaks in daycare centers during the early pandemic (10/2020–06/2021) in Germany. Young children and adults who tested positive for SARS-CoV-2 had two blood samples taken at an interval of five weeks. We found that young children are more likely to develop antibodies after SARS-CoV-2 infection than adults. These findings indicate that young children may be—at least temporarily—protected from re-infection or from a severe course of the disease.
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