However, a study of neutralizing antibodies reveals that vaccinations are protective.
Children who previously had COVID-19 (or the inflammatory condition Multisystem Inflammatory Syndrome in Children) are not protected against the newer Omicron variant, according to research based on the nationwide Overcoming COVID-19 project, which is directed by Boston Children’s Hospital.
The research did discover that vaccination does provide protection, however. The results, which were recently published in Nature Communications, are consistent with those in adults.
“I hear parents say, “Oh, my kid had COVID last year,” says Adrienne Randolph, MD, MSc, of Boston Children’s Hospital, who launched Overcoming COVID-19 in 2020. Randolph was the senior author of the current paper with Surender Khurana, Ph.D., of the Food and Drug Administration’s Division of Viral Products, Center for Biologics Evaluation and Research. “But we found that antibodies produced by prior infections in children don’t neutralize Omicron, meaning that unvaccinated children remain susceptible to Omicron.”
Blood samples were collected from 50 outpatients who had recovered from moderate COVID-19, 62 children and adolescents hospitalized with severe COVID-19, and 65 children and adolescents hospitalized with MIS-C. All of the samples were collected between 2020 and early 2021, before the emergence of the Omicron variant.
In the lab, scientists exposed the samples to a pseudovirus (produced from SARS-CoV-2 but stripped of its virulence) and assessed how effectively antibodies in the samples neutralized five distinct SARS-CoV-2 variants of concern: Alpha, Beta, Gamma, Delta, and Omicron.
Children and teenagers generally exhibited some loss of antibody cross-neutralization against all five types, but Omicron had the most loss.
“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,” says Randolph. “Unvaccinated children remain susceptible.”
In contrast, children who had received two doses of the COVID-19 vaccine showed higher neutralizing antibody titers against the five variants, including Omicron.
Randolph hopes these data will encourage parents to have their children and teens vaccinated. According to data from the CDC, only 28 percent of 5- to 11-year-olds and just 58 percent of 12- to 17-year-olds had received two vaccine doses as of May 18, 2022, numbers that have barely changed since March. An FDA panel will meet on June 15 to consider authorization of COVID-19 vaccines for children under age 5.
The study was funded by the FDA (Perinatal Health Center of Excellence), the U.S. Centers for Disease Control and Prevention (contract #75D30120C07725), and the National Institutes of Health (R01AI084011).
Reference: “Cross-reactive immunity against the SARS-CoV-2 Omicron variant is low in pediatric patients with prior COVID-19 or MIS-C” by Juanjie Tang, Tanya Novak, Julian Hecker, Gabrielle Grubbs, Fatema Tuz Zahra, Lorenza Bellusci, Sara Pourhashemi, Janet Chou, Kristin Moffitt, Natasha B. Halasa, Stephanie P. Schwartz, Tracie C. Walker, Keiko M. Tarquinio, Matt S. Zinter, Mary A. Staat, Shira J. Gertz, Natalie Z. Cvijanovich, Jennifer E. Schuster, Laura L. Loftis, Bria M. Coates, Elizabeth H. Mack, Katherine Irby, Julie C. Fitzgerald, Courtney M. Rowan, Michele Kong, Heidi R. Flori, Aline B. Maddux, Steven L. Shein, Hillary Crandall, Janet R. Hume, Charlotte V. Hobbs, Adriana H. Tremoulet, Chisato Shimizu, Jane C. Burns, Sabrina R. Chen, Hye Kyung Moon, Christoph Lange, Adrienne G. Randolph and Surender Khurana, 27 May 2022, Nature Communications.