To analyze patterns of neutralizing antibodies in children and adolescents following mild severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections

One hundred twenty six participants aged 0 to 16 years with confirmed SARS-CoV-2 infection by nasopharyngeal-polymerase chain reactions. All participants were followed at KK Women’s Children’s Hospital in Singapore from February 1, 2020 to September 30, 2021.

Participant blood samples were obtained at various time points up to 16 months after SARS- CoV-2 infection. Neutralizing antibodies were measured using inhibition enzyme-linked immunosorbent assay. Variables including age, sex, and symptom status were adjusted when analyzing temporal distribution of neutralizing antibody levels.

Mean age of 126 participants was 7.4 years (1 month–16 years), with 74 male (58.7%) and 52 female (41.3%). All symptomatic cases were mild (91 patients or 72%). Peak neutralizing antibody levels were seen 1 to 3 months after infection (median value of 84% via surrogate virus neutralization test) and remained high at 9 to 13 months after infection. After adjusting for sex and symptom status, neutralizing antibody levels were highest in those <5 years of age (71.6%; 95% confidence interval, 58.5%–84.6%) during the acute phase of infection (<1 month), with little change at the end of the study. During the acute phase of infection, those in the 12 to 16 years group had the lowest antibody levels, which peaked at 1 to 3 months after infection.

Neutralizing SARS-CoV-2 antibodies may persist up to 16 months in children and adolescents following a positive polymerase chain reaction-nasopharyngeal test. Younger children <5 years of age especially had rapid production of neutralizing antibodies and maintained their levels over time, compared with older participants of the study.

This study shows that neutralizing SARS-CoV-2 antibodies may be long-lasting in pediatric patients with mild infections. Infants and younger children mount an earlier antibody response that remains stable over time, compared with older children and adolescents. It is worth noting that a decrease in sample size after 9 months postinfection may have affected the statistical significance of the presented results. Potential future directions include comparing antibody responses of those with mild versus severe reactions, as well as comparing responses of children versus adults.