Children who previously had Covid-19 or the inflammatory disease MIS-C, associated with the virus, are not protected against the new variant of Omicron, a study has found.
The study, published in Nature Communications, showed that vaccination does provide protection, however.
Although Covid is rare and mild in children, some of those infected faced severe multisystem inflammatory syndrome (MIS). The United States Centers for Disease Control and Prevention (CDC) defines MIS-C as a condition in which different parts of the body can become inflamed, including the heart, lungs, kidneys, brain, skin, eyes or the gastrointestinal organs.
“I hear parents say, ‘Oh, my child had Covid last year’. But we found that antibodies produced by previous infections in children do not neutralize Omicron, which means unvaccinated children remain sensitive to Omicron,” said Adrienne Randolph of Children’s Hospital Boston.
The researchers obtained blood samples from 62 children and adolescents hospitalized with severe Covid, 65 children and adolescents hospitalized with MIS-C and 50 outpatients who had recovered from mild Covid-19. All samples were taken in 2020 and early 2021, before the emergence of the Omicron variant.
In the lab, they exposed the samples to a pseudovirus (derived from SARS-CoV-2, but stripped of its virulence) and measured how well the antibodies in the samples were able to neutralize five different variants of SARS-CoV- 2 of concern: Alpha, Beta, Gamma, Delta and Omicron.
Overall, children and adolescents showed some loss of antibody cross-neutralization against all five variants, but the loss was more pronounced for Omicron.
“Omicron is very different from previous variants, with many mutations on the spike protein, and this work confirms that it is able to evade the antibody response,” Randolph said. “Unvaccinated children remain susceptible.”
In contrast, children who had received two doses of the Covid-19 vaccine had higher neutralizing antibody titers against all five variants, including Omicron.
Randolph hopes this data will encourage parents to get their children and teens vaccinated. A Food and Drug Administration panel will meet on June 15 to consider the authorization of Covid vaccines for children under 5.
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