Efficacy and Safety of mRNA COVID-19 Vaccines in Children Aged 5-11 Years: A Systematic Review and Meta-Analysis

Abstract

Abstract Background Evidence of the efficacy and safety of mRNA COVID-19 vaccines in children aged 5-11 years have been emerging. Collecting these data will inform clinicians, families, and policymakers. To evaluate the efficacy and safety of mRNA COVID-19 vaccines in children aged 5-11 years, we conducted a systematic review of literatures and meta-analysis. Methods PubMed and EMBASE databases were searched on September 2022 without language restrictions. Randomized controlled trials (RCTs) and observational studies comparing vaccinated versus unvaccinated children aged 5-11 years and reporting efficacy or safety outcomes were included. Studies reporting safety outcomes in vaccinated children only (i.e., no control group) were also included. Two investigators independently extracted relevant data from each study. Odds ratios (ORs) for efficacy and safety outcomes and incidences of adverse events (AEs) following vaccination were synthesized using a random-effects model. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analysis and Meta-analysis of Observational Studies in Epidemiology reporting guidelines. The primary outcome was SARS-CoV-2 infections with or without symptoms. The secondary outcomes included symptomatic SARS-CoV-2 infections, hospitalizations, and multisystem inflammatory syndrome in children (MIS-C). The incidences of each AE following vaccination were also evaluated. Results Two RCTs and 15 observational studies involving 10,935,541 vaccinated (median/mean age, 8.0-9.5 years) and 2,635,251 unvaccinated (median/mean age, 7.0-9.5 years) children were included. Two-dose mRNA COVID-19 vaccination compared to no vaccination was associated with lower risks of SARS-CoV-2 infections with or without symptoms (OR, 0.47; 95% confidence interval [CI], 0.35-0.64) (Figure 1a), symptomatic SARS-CoV-2 infections (OR, 0.53; 95% CI, 0.41-0.70) (Figure 1b), hospitalizations (OR, 0.32; 95% CI, 0.15-0.68) (Figure 1c), and MIS-C (OR, 0.05; 95% CI, 0.02-0.10) (Figure 1d), while it was associated with a higher risk of any AEs compared to placebo (OR, 1.92; 95% CI, 1.26-2.91) (Figure 1e). The incidence of AEs that prevented normal daily activities was 8.8% (95% CI, 5.4-14.2%) (Figure 1f) and that of myocarditis was estimated to be 1.8/million (95% CI, 0.000-0.001%) (Figure 1g) following the second injection. Conclusions COVID-19 mRNA vaccines are safe and effective measures to prevent SARS-CoV-2 infection and severe COVID-19-related illnesses among children aged 5-11 years. Our data provided evidence for future recommendations.