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Evaluation of mRNA-1273 Vaccine in Children 6 Months to 5 Years of Age
Evan J Anderson1, C Buddy Creech1, Vladimir Berthaud1
1From the Center for Childhood Infections and Vaccines, Children's Healthcare of Atlanta, and the Department of Pediatrics, Emory University School of Medicine, Atlanta (E.J.A.), and IResearch Atlanta, Decatur (K.A.J.) - all in Georgia; the Vanderbilt Vaccine Research Program, Department of Pediatrics, Vanderbilt University Medical Center (C.B.C.), and Meharry Medical College (V.B.) - both in Nashville; OnSite Clinical Solutions, Charlotte, NC (A.P.); the Henry Ford Health System, Detroit (M.Z.); Pi-Coor Clinical Research, Burke, VA (F.G.); the Lynn Health Science Institute, Oklahoma City (C.G.); the Cyfair Clinical Research Center (K.P.) and the Texas Center for Drug Development (K.A.), Houston, and ACRC Trials, Frisco (M.A.) - all in Texas; Velocity Clinical Research, Meridian, ID (M.T.); Children's Hospital of Philadelphia Clinical Research Partners, Philadelphia (J.G.); Clinical Research Partners, Richmond, VA (R.L.B.); Clinical Research Institute, Minneapolis (G.B.); the University of Rochester Medical Center, Rochester (J.N.), and Certified Research Associates, Cortland (C.A.S.) - both in New York; Pediatric, Infant, and Adolescent Medicine, Ventura, CA (C.C.); Velocity Clinical Research, West Jordan, UT (B.R.); Ann and Robert H. Lurie Children's Hospital, Chicago (W.J.M.); the University of Kentucky, Lexington (G.F.); the Pennington Biomedical Research Center, Baton Rouge, LA (D.H.); and Moderna, Cambridge, MA (J.E.T., D.D., C.R., B.K., X.Z., W.D., H.Z., D.R.S., K.H., B.G., K.S., R.M., R.P., A.A., R.D., J.M.M., S.S.G.).
Insights
The mRNA-1273 vaccine, at two 25-μg doses, is safe and effective for children aged 6 months to 5 years. It generated immune responses comparable to young adults, showing efficacy against COVID-19 during the Omicron variant surge.
Area of Science:
- Vaccinology
- Pediatric Infectious Diseases
- Immunology
Background:
- The safety, reactogenicity, immunogenicity, and efficacy of the mRNA-1273 vaccine in young children (6 months to 5 years) were previously unknown.
- Understanding vaccine performance in pediatric populations is crucial for public health strategies against coronavirus disease 2019 (COVID-19).
Purpose of the Study:
- To evaluate the safety and reactogenicity of a two-dose 25-μg regimen of the mRNA-1273 vaccine in children aged 6 months to 5 years.
- To determine if the immune response in these children is noninferior to that observed in young adults.
- To assess the vaccine's efficacy against COVID-19 and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.
Main Methods:
- A phase 2-3, observer-blinded, placebo-controlled trial (Part 2) involving children aged 6 months to 5 years.
- Random assignment of participants to receive two 25-μg injections of mRNA-1273 or placebo, 28 days apart.
- Primary endpoints included safety, reactogenicity, and noninferiority of immune responses compared to young adults; secondary endpoints included incidence of COVID-19 and SARS-CoV-2 infection.
Main Results:
- The 25-μg dose was found safe and well-tolerated, with mainly low-grade and transient adverse events.
- Neutralizing antibody geometric mean concentrations met noninferiority criteria when compared to young adults who received a higher dose.
- Estimated vaccine efficacy against COVID-19 was 36.8% in 2-5 year olds and 50.6% in 6-23 month olds during Omicron predominance.
Conclusions:
- Two 25-μg doses of the mRNA-1273 vaccine are safe and elicit noninferior immune responses in children aged 6 months to 5 years compared to young adults.
- The findings support the use of the mRNA-1273 vaccine in this pediatric age group.
- The study was funded by BARDA and NIAID and registered under NCT04796896.
Background:
The safety, reactogenicity, immunogenicity, and efficacy of the mRNA-1273 coronavirus disease 2019 (Covid-19) vaccine in young children are unknown.
Methods:
Part 1 of this ongoing phase 2-3 trial was open label for dose selection; part 2 was an observer-blinded, placebo-controlled evaluation of the selected dose. In part 2, we randomly assigned young children (6 months to 5 years of age) in a 3:1 ratio to receive two 25-μg injections of mRNA-1273 or placebo, administered 28 days apart. The primary objectives were to evaluate the safety and reactogenicity of the vaccine and to determine whether the immune response in these children was noninferior to that in young adults (18 to 25 years of age) in a related phase 3 trial. Secondary objectives were to determine the incidences of Covid-19 and severe acute respiratory syndrome coronavirus 2 infection after administration of mRNA-1273 or placebo.
Results:
On the basis of safety and immunogenicity results in part 1 of the trial, the 25-μg dose was evaluated in part 2. In part 2, 3040 children 2 to 5 years of age and 1762 children 6 to 23 months of age were randomly assigned to receive two 25-μg injections of mRNA-1273; 1008 children 2 to 5 years of age and 593 children 6 to 23 months of age were randomly assigned to receive placebo. The median duration of follow-up after the second injection was 71 days in the 2-to-5-year-old cohort and 68 days in the 6-to-23-month-old cohort. Adverse events were mainly low-grade and transient, and no new safety concerns were identified. At day 57, neutralizing antibody geometric mean concentrations were 1410 (95% confidence interval [CI], 1272 to 1563) among 2-to-5-year-olds and 1781 (95% CI, 1616 to 1962) among 6-to-23-month-olds, as compared with 1391 (95% CI, 1263 to 1531) among young adults, who had received 100-μg injections of mRNA-1273, findings that met the noninferiority criteria for immune responses for both age cohorts. The estimated vaccine efficacy against Covid-19 was 36.8% (95% CI, 12.5 to 54.0) among 2-to-5-year-olds and 50.6% (95% CI, 21.4 to 68.6) among 6-to-23-month-olds, at a time when B.1.1.529 (omicron) was the predominant circulating variant.
Conclusions:
Two 25-μg doses of the mRNA-1273 vaccine were found to be safe in children 6 months to 5 years of age and elicited immune responses that were noninferior to those in young adults. (Funded by the Biomedical Advanced Research and Development Authority and National Institute of Allergy and Infectious Diseases; KidCOVE ClinicalTrials.gov number, NCT04796896.).
