Children with mild or asymptomatic COVID have strong antibodies

DURHAM, N.C. – Children and adolescents who had mild to asymptomatic cases of COVID-19 were found to have robust antibody responses up to four months after infection, according to a study of 69 children tested at Duke Health.

The study, appearing in the journal JCI Insight, found that the children and adolescents who previously had COVID-19 developed antibody responses that were capable of neutralizing the SARS-CoV-2 virus. Further, these responses were comparable or superior to those observed in adults.

“These findings are encouraging, especially because we cannot yet vaccinate children under the age of 12 against the virus,” said co-lead author Jillian Hurst, PhD, assistant professor in the Department of Pediatrics at Duke University School of Medicine. “The study shows that children who’ve had mild infections or even those who did not have any symptoms, develop an immune response that will likely provide some protection against future infections.”

The researchers -- including senior authors Genevieve Fouda, MD, PhD, associate professor in the departments of Pediatrics and Molecular Genetics and Microbiology at Duke University School of Medicine and Matthew Kelly, MD, assistant professor in Pediatrics, and co-first author Carolina Garrido, PhD, of the Duke Human Vaccine Institute -- evaluated the SARS-CoV-2-specific immune responses in 69 children and adolescents, with ages ranging from 2 months old to 21 years-old. The median age of participants was 11.5 years, and 51% were female.

The antibody response suggests some protection against re-infection

The researchers measured antibody responses among children and adolescents with asymptomatic and mild symptomatic SARS-CoV-2 infection and found that the antibody response did not differ based on the presence of symptoms, and SARS-CoV-2 neutralizing antibodies remained detectable in the majority of participants up to four months after infection.

The researchers also compared the children’s immune responses to those of adults. They found that all children, regardless of age group, had equivalent or slightly higher levels of antibodies than adults at two months and four months after acute infection.

“Most studies of the immune responses of children to SARS-CoV-2 have focused on patients hospitalized for severe COVID-19 or multi-system inflammatory syndrome in children (MIS-C), or have assessed immunity only during acute infection,” Fouda said. “Our study provides important information that SARS-CoV-2-specific immune responses, regardless of disease severity, may decline over time more slowly in children and adolescents.”

Study authors said the findings suggest vaccinating young children against COVID-19 could also elicit a similar or greater degree of protection than that of adults.

In addition to Fouda, Kelly, Hurst and Garrido, study authors include Cynthia G. Lorang, Jhoanna N. Aquino, Javier Rodriguez, Trevor S. Pfeiffer, Tulika Singh, Eleanor C. Semmes, Debra J. Lugo, Alexandre T. Rotta, Nicholas A. Turner, Thomas W. Burke, Micah T. McClain, Elizabeth A. Petzold, Sallie R. Permar, M. Anthony Moody and Christopher W. Woods.

The study received funding from the Duke University School of Medicine, the U.S. Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, the National Institutes of Health (U01AI066569, UM1AI104681), the U.S. Defense Advanced Projects Agency (N66001-09-C- 2082, HR0011-17-2-0069), and Virology Quality Assurance (75N93019C00015). COVID-19 samples were processed at the Duke Regional Biocontainment Laboratory, which received partial support for construction from NIH (UC6AI058607).

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