Background A 2-dose mRNA-1273 primary series in children aged 6 months–5 years (25 µg) and 6–11 years (50 µg) had an acceptable safety profile and was immunogenic in the phase 2/3 KidCOVE study. We present data from KidCOVE participants who received an mRNA-1273 booster dose. Methods An mRNA-1273 booster dose (10 µg for children aged 6 months–5 years; 25 µg for children aged 6–11 years; age groups based on participant age at enrollment) was administered ≥6 months after primary series completion. The primary safety objective was the safety and reactogenicity of an mRNA-1273 booster dose. The primary immunogenicity objective was to infer efficacy of an mRNA-1273 booster dose by establishing noninferiority of neutralizing antibody (nAb) responses after a booster in children versus nAb responses observed after the mRNA-1273 primary series in young adults (18–25 years) from the pivotal efficacy study. Data were collected from March 2022 to June 2023. Results Overall, 153 (6 months–5 years) and 2519 (6–11 years) participants received an mRNA-1273 booster dose (median age at receipt of booster: 2 and 10 years, respectively). The booster dose safety profile was generally consistent with that of the primary series in children; no new safety concerns were identified. An mRNA-1273 booster dose elicited robust nAb responses against ancestral SARS-CoV-2 among children and met prespecified noninferiority success criteria versus responses observed after the primary series in young adults. Conclusions Safety and immunogenicity data support administration of an mRNA-1273 booster dose in children aged 6 months to 11 years. Clinical Trials Registration NCT04796896 (Clinicaltrials.gov).

中文翻译：

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mRNA-1273 加强剂在儿童中的安全性和免疫原性


背景 在 6 个月-5 岁 （25 μg） 和 6-11 岁 （50 μg） 儿童中接种 2 剂 mRNA-1273 初级系列疫苗具有可接受的安全性，并且在 2/3 期 KidCOVE 研究中具有免疫原性。我们提供了来自接受 mRNA-1273 加强剂量的 KidCOVE 参与者的数据。方法 在初级系列完成后 ≥6 个月）给予 mRNA-1273 加强剂量（6 个月-5 岁儿童 10 μg;6-11 岁儿童 25 μg;年龄组基于参与者入组时的年龄）。主要安全目标是 mRNA-1273 加强剂量的安全性和反应原性。主要免疫原性目标是通过确定儿童加强后中和抗体 （nAb） 反应与年轻人 （18-25 岁） mRNA-1273 初级系列后观察到的 nAb 反应的非劣效性来推断 mRNA-1273 加强剂量的疗效关键疗效研究。数据收集时间为 2022 年 3 月至 2023 年 6 月。结果总体而言，153 名（6 个月-5 岁）和 2519 名（6-11 岁）参与者接受了 mRNA-1273 加强剂量（接受加强剂的中位年龄：分别为 2 岁和 10 岁）。儿童加强剂量安全性与初级系列研究基本一致;未发现新的安全问题。mRNA-1273 加强剂量在儿童中引发了对祖先 SARS-CoV-2 的强烈 nAb 反应，并且与年轻人初级系列后观察到的反应相比，符合预先指定的非劣效性成功标准。结论 安全性和免疫原性数据支持对 6 个月至 11 岁儿童进行 mRNA-1273 加强剂量。临床试验注册NCT04796896 （Clinicaltrials.gov）.