Kids have higher concentration of neutralizing antibodies after mild COVID infection compared to adults: Study

SARS-CoV-2 infection in children is less severe than in adults, resulting in underdiagnosis given the mild or asymptomatic clinical course but they play key role in transmission of disease. Little is known about the kinetics of SARSCoV-2 nAbs(neutralizing antibodies) in pediatric populations, henceforth understanding the differences in the antibody response between adults and children has important scientific and public health implications, including design of risk-based surveillance programs.

Bonfante et al conducted an observational study to study the trends in neutralizing antibody titers following COVID-19 infection in a cluster of families and found children had higher nAbs.

A single-center, prospective observational study was conducted on 57 family clusters of coronavirus disease 2019, including children of neonatal and pediatric age attending the COVID-19 followup clinic. Participants were recruited only if they had a record of virological positivity for SARS-CoV2 by real-time polymerase chain reaction (RT-PCR) according to routine diagnostic molecular protocols and at followup for each patient, blood samples were collected for both the quantification of nAbs through a plaque reduction neutralizing test and the detection of antinucleocapsid-spike protein immunoglobulin G and/or immunoglobulin M.

Key findings of the study are:

-Upon analysis of 283 blood samples from confirmed COVID-19 patients, nAbs persisted for a median of 132 days and on subgroup analysis children less than 6 years had increasing trend as opposed against 6-15 years children and adults.

-nAbs inversely correlated with age, and children aged <3 years had the highest titers throughout early ,intermediate and late times from infection onset.

-Difference in the viral load at time of active infection were not significant- adults recorded a mean viral load of 107.88 copies, whereas children aged <6 years had 107.645 and 6-15 years children had 106.79.

Authors conclude-"Younger children develop higher levels of nAbs during the first 7 to 8 months after asymptomatic or mild symptomatic coronavirus disease 2019, compared with older siblings and adults. The long lasting levels of nAbs may lead to durable protection and higher viral clearance, reducing shedding and transmission."

Source: Bonfante F, Costenaro P, Cantarutti A, Di Chiara C, Bortolami A, Petrara MR, Carmona F, Pagliari M, Cosma C, Cozzani S, Mazzetto E, Di Salvo G, Da Dalt L, Palma P, Barzon L, Corrao G, Terregino C, Padoan A, Plebani M, De Rossi A, Donà D, Giaquinto C. Mild SARS-CoV-2 Infections and Neutralizing Antibody Titers. Pediatrics. 2021 Sep;148(3):e2021052173. doi: 10.1542/peds.2021-052173.