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Earlier Infection Doesn’t Appear to Protect Children Well Against COVID-19

A common assumption among parents and caregivers is that children who have been previously infected with SARS-CoV-2 don’t need to be vaccinated. A new study proves that theory wrong, however, noting that only 10% of children and adolescents infected with COVID-19 in 2020 or early 2021 developed enough antibodies to protect them against the Omicron variant. Here is more information.

SILVER SPRING, MD – When parents and caregivers argue that their child doesn’t need a COVID-19 vaccine because they already were infected with SARS-CoV-2, pharmacists and other vaccinators now have a ready response.

They might point out that more than 90% of children who were infected with COVID-19 in 2020 or early 2021 failed to develop enough antibodies to fight off the Omicron variant of SARS-CoV-2.

Researchers from the U.S. Food and Drug Administration, Harvard Medical School and Boston Children’s Hospital emphasize that the pediatric population has been understudied in the novel coronavirus pandemic but understanding children’s response to SARS-CoV-2 Omicron and emerging variants is essential for disease management, development of therapeutics, and refinement of vaccines.

Published in Nature Communications, their study of children and adolescents younger than 21 and who were previously infected with SARS-CoV-2 between April 2020 and March 2021 revealed an age-dependent effect in the neutralization of five different SARS-CoV-2 variants of concern (VOCs).

“The most prominently reduced antibody neutralization occurred in the youngest children with acute COVID-19 compared with older age groups,” according to the authors, who add that Multisystem inflammatory syndrome in children (MIS-C) patients and convalescent outpatients who had mild COVID-19 showed similar responses across all ages.

“Overall, results suggest a differentially evolving quantitative and qualitative neutralizing response to SARS-CoV-2 and VOCs in children less than 5 years old and who are currently ineligible for vaccination,” the study notes. “This is especially important as children in this study were infected with SARS-CoV-2 prior to the circulation of Delta or Omicron did not have neutralizing antibodies against Omicron and therefore are likely susceptible to re-infection with the Omicron variant.”

Background information in the article advises that recent research using cellular immune profiling indicates that systemic immune response in the blood of children is characterized by a more naive state compared with a more memory-based immune repertoire in adults.

“To our knowledge, this is the first evaluation of antibody response to Omicron in convalescent COVID-19 and MIS-C pediatric patients, who are potentially at risk of re-infection with Omicron or newly emerging SARS-CoV-2 variants, as has been observed in adults,” the authors write. “A significant strength of this study is that the pediatric acute and MIS-C samples were from a U.S. national multicenter cohort collected during the pandemic, increasing generalizability.”

Researchers explain that their findings suggest that the antibodies produced by previous SARS-CoV-2 infection in the pediatric population do not neutralize the currently circulating Omicron variant. That means the children potentially remain susceptible to re-infection with Omicron.

“Vaccine-induced a much broader neutralizing antibody response against VOCs in naïve children compared with the natural immunity induced following SARS-CoV-2 infection,” they add, noting, “Our study highlights the importance of vaccinating children and younger adolescents even with preexisting antibody immunity by an earlier SARS-CoV-2 strain to prevent severe disease in children from Omicron and future infections.”