Interim Safety and Immunogenicity of COVID-19 Omicron-BA.1 Variant-Containing Vaccine in Children

Objectives We report interim safety and immunogenicity results from a phase 3 study of omicron-BA.1 variant-containing (mRNA-1273.214) primary vaccination series (Part 1) and booster dose (Part 2) in children aged 6 months to 5 years ([NCT05436834][1]). Methods In Part 1, SARS-CoV-2 unvaccinated participants, including participants who received placebo in the KidCOVE study ([NCT04796896][2]), received 2 doses of mRNA-1273.214 (25-μg omicron-BA.1 and ancestral Wuhan-Hu-1 mRNA 1:1 co-formulation) primary series. In Part 2, participants who previously completed the mRNA-1273 (25-µg) primary series in KidCOVE received a mRNA-1273.214 (10-μg) booster dose. Primary objectives were safety, reactogenicity, and immunogenicity, including prespecified immune response success criteria. Results At the data cutoff (December 5, 2022), 179 participants had received ≥1 dose of mRNA-1273.214 primary series (Part 1) and 539 participants had received a mRNA-1273.214 booster dose (Part 2). The safety profile of mRNA-1273.214 primary series and booster dose was consistent with that of the mRNA-1273 primary series in this same age group, with no new safety concerns identified and no vaccine-related serious adverse events observed. Compared with neutralizing antibody responses induced by the mRNA-1273 primary series, both the mRNA-1273.214 primary series and booster elicited responses that were superior against omicron-BA.1 and non-inferior against ancestral Wuhan-Hu-1(D614G). Conclusions mRNA-1273.214 was immunogenic against BA.1 and D614G in children aged 6 months to 5 years, with a comparable safety profile to mRNA-1273, when given as a 2-dose primary series or as a booster dose after the mRNA-1273 primary series. Clinical Trial Registry NCT05436834 ### Competing Interest Statement AD, RP, KH, BG, WZ, WD, HZ, SSG, JMM, and RD are employees of Moderna, Inc., and hold stock/stock options in the company. AY, KS and BJK are consultants for Moderna, Inc. ### Clinical Trial NCT05436834 ### Funding Statement This work was supported by Moderna, Inc. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The protocol and study documents were approved before conduct of study procedures (Advarra Institutional Review Board). Written informed consent from parent(s)/legally authorized representative(s) of children was obtained before performing study procedures. The study was conducted in accordance with the protocol, ethical principles derived from international guidelines that including the Declaration of Helsinki and Council for International Organizations of Medical Sciences International Ethical Guidelines, International Council for Harmonisation Good Clinical Practice guidelines, and laws and regulatory requirements. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes As the trial is ongoing, access to patient-level data presented in the article (immunogenicity, safety, and reactogenicity) and supporting clinical documents by qualified external researchers who provide methodologically sound scientific proposals may be available upon reasonable request and subject to review once the trial is complete. Such requests can be made to Moderna, Inc., 200 Technology Square, Cambridge, MA 02139. A materials transfer and/or data access 343 agreement with the sponsor will be required for accessing shared data. All other relevant data are presented in the paper. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT05436834&atom=%2Fmedrxiv%2Fearly%2F2023%2F06%2F29%2F2023.06.23.23291767.atom [2]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT04796896&atom=%2Fmedrxiv%2Fearly%2F2023%2F06%2F29%2F2023.06.23.23291767.atom