Durability of Original Monovalent mRNA Vaccine Effectiveness Against COVID-19 Omicron–Associated Hospitalization in Children and Adolescents — United States, 2021–2023
Authors: Laura D. Zambrano, Margaret M. Newhams, Regina M. Simeone, Amanda B. Payne, Michael Wu, Amber O. Orzel-Lockwood, Natasha B. Halasa, Jemima M. Calixte, Pia S. Pannaraj, Kanokporn Mongkolrattanothai, Julie A. Boom, Leila C. Sahni, Satoshi Kamidani, Kathleen Chiotos, Melissa A. Cameron, Aline B. Maddux, Katherine Irby, Jennifer E. Schuster, Elizabeth H. Mack, Austin Biggs, Bria M. Coates, Kelly N. Michelson, Katherine E. Bline, Ryan A. Nofziger, Hillary Crandall, Charlotte V. Hobbs, Shira J. Gertz, Sabrina M. Heidemann, Tamara T. Bradford, Tracie C. Walker, Stephanie P. Schwartz, Mary Allen Staat, Samina S. Bhumbra, Janet R. Hume, Michele Kong, Melissa S. Stockwell, Thomas J. Connors, Melissa L. Cullimore, Heidi R. Flori, Emily R. Levy, Natalie Z. Cvijanovich, Matt S. Zinter, Mia Maamari, Cindy Bowens, Danielle M. Zerr, Judith A. Guzman-Cottrill, Ivan Gonzalez, Angela P. Campbell, Adrienne G. Randolph, Meghan Murdock, Heather Kelley, Candice Colston, Ronald C. Sanders, Laura Miron, Masson Yates, Ashlyn Madding, Alexa Dixon, Michael Henne, Kathleen Sun, Jazmin Baez Maidana, Natalie Triester, Jaycee Jumarang, Daniel Hakimi, Kennis-Grace Mrotek, Liria Muriscot Niell, Natasha Baig, Elizabeth Temte, Lexi Petruccelli, Heidi Sauceda, Nicolette Gomez, Mark D. Gonzalez, Caroline R. Ciric, Jong-Ha C. Choi, Elizabeth G. Taylor, Grace X. Li, Nadine Baida, Heather E. Price, Mary Stumpf, Suden Kucukak, Eve Listerud, Maya Clark, Rylie Dittrich, Allison Zaff, Patrick Moran, Jessica C. Peterson, Noelle M. Drapeau, Lora Martin, Lacy Malloch, Maygan Martin, Cameron Sanders, Kayla Patterson, Melissa Sullivan, Shannon Pruitt, Elizabeth Ricciardi, Celibell Y. Vargas, Raul A. Silverio Francisco, Ana Valdez de Romero, Sheila Joshi, Merry Tomcany, Nicole Twinem, Chelsea C. Rohlfs, Amber Wolfe, Rebecca Douglas, Kathlyn Phengchomphet, Jenny Bush, Alanah Mckelvey, Mickael Boustany, Fatima A. Mohammed, Laura S. Stewart, Kailee Fernandez, Leenah Abojaib, Molly J. Kyles, Amanda Adler
Journal: MMWR Morbidity and Mortality Weekly Report (2024)

Pediatric COVID-19 vaccination is effective in preventing COVID-19-related hospitalization, but duration of protection of the original monovalent vaccine during SARS-CoV-2 Omicron predominance merits evaluation, particularly given low coverage with updated COVID-19 vaccines.During December 19, 2021-October 29, 2023, the Overcoming COVID-19 Network evaluated vaccine effectiveness (VE) of ≥2 original monovalent COVID-19 mRNA vaccine doses against COVID-19-related hospitalization and critical illness among U.S. children and adolescents aged 5-18 years, using a case-control design.Too few children and adolescents received bivalent or updated monovalent vaccines to separately evaluate their effectiveness.Most case-patients (persons with a positive SARS-CoV-2 test result) were unvaccinated, despite the high frequency of reported underlying conditions associated with severe COVID-19.VE of the original monovalent vaccine against COVID-19-related hospitalizations was 52% (95% CI = 33%-66%) when the most recent dose was administered <120 days before hospitalization and 19% (95% CI = 2%-32%) if the interval was 120-364 days.VE of the original monovalent vaccine against COVID-19-related hospitalization was 31% (95% CI = 18%-43%) if the last dose was received any time within the previous year.VE against critical COVID-19-related illness, defined as receipt of noninvasive or invasive mechanical ventilation, vasoactive infusions, extracorporeal membrane oxygenation, and illness resulting in death, was 57% (95% CI = 21%-76%) when the most recent dose was received <120 days before hospitalization, 25% (95% CI = -9% to 49%) if it was received 120-364 days before hospitalization, and 38% (95% CI = 15%-55%) if the last dose was received any time within the previous year.VE was similar after excluding children and adolescents with * These senior authors contributed equally to this report.documented immunocompromising conditions.Because of the low frequency of children who received updated COVID-19 vaccines and waning effectiveness of original monovalent doses, these data support CDC recommendations that all children and adolescents receive updated COVID-19 vaccines to protect against severe COVID-19.