Immunogenicity,effectiveness,and safety of COVID‑19 vaccines among children and adolescents aged 2–18 years:an updated systematic review and meta‑analysis

Background During the coronavirus disease 2019(COVID-19)pandemic,there is an urgent need for safe and effective COVID-19 vaccines to protect children and adolescents.This study aims to provide scientific evidence and recommendations for the application of COVID-19 vaccines in children and adolescents by analyzing the latest studies.Methods We systematically searched MEDLINE(accessed through PubMed),Embase,and Web of Science from January 1,2020,to October 8,2022.Eligible clinical trials,cohort studies,case‒control studies,and cross-sectional studies with extractable data were included in immunogenicity,effectiveness,and safety analyses.According to the heterogeneity,we chose a fixed-effect model(when I2≤50)or a random-effects model(when I2>50)to pool effect values.Results A total of 88 articles were included.The seroconversion rates after the first,second,and third doses of the vaccines were 86.10%,96.52%,and 99.87%,respectively.After the first and second doses,vaccine effectiveness(VE)against severe acute respiratory syndrome coronavirus 2 infection was 42.87%[95%confidence interval(CI)=27.09%–58.65%]and 63.33%(95%CI=52.09%–74.56%),respectively.After the first and second doses,VE against COVID-19 was 60.65%(95%CI=44.80%–76.50%)and 75.77%(95%CI=63.99%–87.56%),respectively.VE against hospitalization due to COVID-19 after the first and second doses was 72.74%(95%CI=51.48%–94.01%)and 82.78%(95%CI=75.78%–89.78%),respectively.The most common adverse events were injection site pain,fatigue/asthenia/tiredness,headache,myalgia/muscle pain,and chills.The incidence rate of myocarditis or pericarditis was 2.42/100,000 people.In addition,the subgroup analysis showed that children aged≤5 years had the lowest incidence of adverse events,and the incidence rate of adverse events was higher for mRNA vaccines than for inactivated vaccines.Conclusions COVID-19 vaccines have good immunogenicity,effectiveness,and safety among children and adolescents.We recommend that children and adolescents be vaccinated as soon as possible to protect them and slow the spread of COVID-19.