Vaccines for COVID-19 proved to be effective in preventing infection and severe illness in children aged 5 to 11, according to a new review published in JAMA Pediatrics.
Severe adverse events (AEs) from the vaccine, which reduced hospitalizations and multisystem inflammatory syndrome in children (MIS-C), were rare; the AEs that did occur resolved within a few days.
Children were thought to be less likely to experience severe symptoms of COVID-19 in the early stages of the pandemic; this was later found to be untrue. This review and meta-analysis aimed to pool current evidence of the efficacy and safety of mRNA COVID-19 vaccines in this age group.
The researchers first used PubMed and Embase to search for literature on the subject on September 29, 2022. A manual search of secondary sources was conducted as well. Studies that were published in a peer-reviewed journal, were human subject studies with children aged 5 to 11 years, studies that compared vaccinated and unvaccinated children, studies that reported the safety outcomes of children with the vaccine, and studies that investigated mRNA vaccines were all included in the review.
Characteristics at baseline, such as age, sex, ethnicity, and preexisting comorbidities among others, were all extracted from the studies. The primary outcome was evaluating COVID-19 infections that were symptomatic and asymptomatic. The secondary outcome was COVID-19 infections with symptoms, hospitalizations, and any reported AEs, including ones that prevented normal activities.
The review included 2 randomized controlled trials and 15 observational studies, including 3 case-control studies and 12 cohort studies. A total of 10,935,541 vaccinated children were included, with a mean or median age range of 8.0-9.5 years across the studies; 46.0%-55.9% made up of girls.
There were 2,635,251 unvaccinated children included with a mean or median age range of 7.0-9.5 years; 44.3%-51.7% were made up of girls. Follow-up duration was 7 to 90 days.
Lower risks of infection with or without symptoms was found in children who had received the 2-dose mRNA COVID-19 vaccination compared with children without vaccination (odds ratio [OR], 0.47; 95% CI, 0.35-0.64). Children with the vaccination also had lower risks of symptomatic COVID-19 infections (OR, 0.53; 95% CI, 0.41-0.70), hospitalizations due to COVID-19 (OR, 0.32; 95% CI, 0.15-0.68), and multisystem inflammatory syndrome in children (MIS-C) (OR, 0.05; 95% CI, 0.02-0.10).
A higher risk of AEs was found in children with the vaccine compared with placebos (OR, 1.92; 95% CI, 1.26-2.91) and associated with higher risks of AEs that prevented normal activities, although not significantly (OR, 1.86; 95% CI, 0.39-8.94). Lower risks of symptomatic COVID-19 were found to continue in the omicron-predominant period of the pandemic.
Children with the vaccine experienced at least 1 AE after the first injection (86.3%; 95% CI, 74.1%-93.3%) and the second injection (86.3%; 95% CI, 73.8%-93.4%).
A far fewer number of children with the vaccine developed a systemic AE after the first injection (45.1%; 95% CI, 34.3%-56.5%) and second injection (56.4%; 95% CI, 38.8%-72.5%).
AEs that prevented daily activities was observed in 4.9% (95% CI, 3.1%-7.7%) following the first vaccination and 8.8% (95% CI, 5.4%-14.2%) following the second injection. The median duration for each symptom ranged from 1 to 2 days, except for local pain and redness which could last for 3 or more days.
There were some limitations to this study. Most of the studies included only evaluated the effects of 1 mRNA vaccine, which makes the validity of the findings unclear. A 1-group meta-analysis was used to estimate incidence of AEs. Therefore, the incidence may have been underestimated. Detailed histories and patient characteristics of AEs were not available. Efficacy against post-COVID conditions is unknown. Lastly, only 1 study evaluated the efficacy of the vaccine with the third dose included.
The researchers concluded that their meta-analysis proved that COVID-19 vaccination was associated with lower risk of infection, related illnesses, and hospitalizations in children aged 5 to 11.
Watanabe A, Kani R, Iwagami M, Takagi H, Yasuhara J, Kuno T. Assessment of efficacy and safety of mRNA COVID-19 vaccines in children aged 5 to 11 years: a systematic review and meta-analysis. JAMA Pediatr. Published online January 23, 2023. doi:10.1001/jamapediatrics.2022.6243