Since children’s developing immune systems seem to react to the coronavirus differently than the adults, the agency is prioritizing safety. Clinical trials are underway to determine COVID-19 vaccines’ side effects in children, but some rare conditions may only emerge when the vaccine is already in wide use among children. A possible way to address this is to conduct large studies over a small period of time, rather than observe a small group of vaccinated children over a longer period.
Additionally, the FDA is concerned about how effective COVID-19 vaccines are in children. Clinical trials usually measure vaccines’ efficacy by comparing symptomatic infections in vaccinated participants versus participants who received a placebo. Since symptomatic COVID-19 infection is less likely in children than adults, it could take a long time for clinical trials to reach the FDA’s statistical requirement for efficacy. The agency may take a different approach to measuring efficacy, such as analyzing the amount of antibodies children produce post-vaccination.
Since most routine vaccinations are administered during childhood, the FDA is also working to determine whether administering COVID-19 vaccines alongside other shots will reduce efficacy or lead to more severe side effects.
