Previous COVID infection does not protect children against Omicron, study says

BOSTON — Children are still susceptible to Omicron, even if they’ve already recovered from an earlier bout with COVID-19 or the inflammatory condition MIS-C. That’s the main finding by researchers at Boston’s Children’s Hospital. The team says the absolute best way to protect children from Omicron is vaccination.

“I hear parents say, ‘Oh, my kid had COVID last year,’” says senior study author Adrienne Randolph, MD, MSc, of Boston Children’s Hospital, in a media release. “But we found that antibodies produced by prior infections in children don’t neutralize Omicron, meaning that unvaccinated children remain susceptible to Omicron.”

These findings are based on blood samples taken from 62 children and adolescents hospitalized with severe cases of COVID-19, another 65 kids hospitalized with MIS-C, and 50 additional outpatients who had mild COVID-19 symptoms. All of those samples come from patients in 2020 or early 2021, before Omicron arrived on the world stage.

MIS-C can be a serious side-effect of a COVID infection among children. Characterized by organ dysfunction, a fever, and inflammation, MIS-C usually develops weeks after recovering from COVID-19. Concerningly, previous studies show the condition can lead to long-lasting damage to a child’s heart.

Omicron continues to break through more than other strains

In a lab setting, researchers exposed the blood samples to a pseudovirus, a virus made from SARS-CoV-2, only without its virulence. Upon exposure, study authors observed and measured how well antibodies in the samples neutralized five distinct SARS-CoV-2 variants: Alpha, Beta, Gamma, Delta, and Omicron.

Generally, patients showed at least some loss of antibody cross-neutralization against all five variants. However, Omicron produced the biggest observed drop in cross-protection by far.

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,” Dr. Randolph adds. “Unvaccinated children remain susceptible.”

Conversely, fully vaccinated adolescent patients displayed much higher neutralizing antibody titers against all five variants, even Omicron.

In conclusion, study authors hope their work helps encourage parents to get their kids vaccinated. As of May 18, 2022, the CDC reports that only 28 percent of five to 11-year-olds and just 58 percent of 12 to 17-year-olds have received two vaccine doses.

The study is published in the journal Nature Communications.

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