US authorities ask vaccine-makers to expand safety studies on children

Measure aims to detect possible rare side effects including heart inflammation

At the urging of federal regulators in the United States, two coronavirus vaccine-makers are expanding the size of their studies in children aged five to 11 – a precautionary measure intended to detect rare side effects including heart inflammation problems that turned up in vaccinated people under age 30.

Multiple people familiar with the trials said the Food and Drug Administration (FDA) had indicated to the two vaccine-makers, Pfizer-BioNTech and Moderna, that the size and the scope of their paediatric studies, as initially envisioned, were inadequate to detect the rare side effects. Those include myocarditis, an inflammation of the heart muscle, and pericarditis, inflammation of the lining around the heart.

Questions about vaccinating children – including those under 12 – are of huge interest to parents and teachers. Regulators will be required to balance potential side effects of coronavirus vaccination against the risks of Covid-19.

Members of a Centers for Disease Control and Prevention advisory committee have said that the benefits of shots for people older than 12 greatly outweigh the risks, including of heart problems. Children in the US aged 12 and older have been eligible for the Pfizer shot for months, even as studies continue on the safety of the Pfizer and Moderna vaccines for younger children.


Double participants

The FDA has asked the companies to include 3,000 children in the five to 11-year-old age group, the group of younger children for which results were expected first, according to people familiar with the situation. That is double the original number of study participants envisioned in the Pfizer trial for that age group, two people said. The study initially sought to enrol 4,500 patients under 12, split into a group of five to 11 year olds and two younger age groups, according to a government website.

A spokesperson for Moderna, Ray Jordan, confirmed that the company intended to expand its trial "to enrol a larger safety database, which increases the likelihood of detecting rarer events", and expected to seek emergency authorisation in "winter 2021/early 2022".

Reviewing all the safety and efficacy data will most likely take regulators at least a few weeks. – New York Times