SARS-CoV-2 antibodies in kids after COVID may peak at 1 to 3 months

In a group of nonhospitalized children 0 to 16 years old, SARS-CoV-2 neutralizing antibody levels peaked at about 84% 1 to 3 months after they tested positive for COVID-19 but remain high for more than a year, finds a single-center study published yesterday in JAMA Pediatrics.The study involved pre-Omicron strains and also found that antibody response in the first month after infection was most durable in participants younger than 5 years.From Feb 1, 2020, to Sep 30, 2021, researchers in Singapore analyzed SARS-CoV-2 neutralizing antibody responses in 126 children aged 0 to 16 years for up to 16 months after COVID-19 diagnosis.

Average participant age was 7.4 years, 58.7% were boys, and 30% completed two to four visits for blood sampling.Antibodies still 70% at 9 to 13 monthsAll patients with COVID-19 symptoms (72%) had a mild illness.

The most common symptoms were fever, cough, and a runny nose. No patients developed multisystem inflammatory syndrome in children (MIS-C).SARS-CoV-2 neutralizing antibody levels peaked at a median of 84% roughly 1 to 3 months after infection and remained at roughly 69.8% after 9 to 13 months.

An adjusted analysis showed no association between neutralizing antibody levels by time since infection and patient characteristics such as sex and symptom status.In the first month after infection, children younger than 5 years had the highest antibody levels (71.6%; 95% confidence interval [CI], 58.5% to 84.6%), while those aged 12 to 16 had the lowest (49.9%; 95% CI, 41.3% to 58.6%).