Pfiser and Moderna are expanding the size of their vaccine trials for children 5 to 11 years old, seeking to better detect very rare heart issues among those vaccinated.
The major vaccine makers are increasing the number of children enrolled in their studies at the prompting of the federal Food and Drug Administration, first reported by The New York Times.
The FDA asked the companies to include 3,000 children or double the previous number of participants in order to be adequately able to detect rare side effects such as myocarditis or pericarditis, inflammations of the heart, according to unnamed sources who spoke to the Times.
The side effect is very unlikely, showing up in only 12.6 cases per 1 million second doses, according to the US Centers for Disease Control and Prevention (CDC). Last month, the FDA updated its vaccine fact sheets to include the possible increased risk. Coronavirus cases are on the rise across the country as the highly contagious delta variant spreads, with cases and deaths overwhelmingly among people who are unvaccinated.
The Pfiser-BioNTech vaccine has already been authorised for children 12 and older, and the Moderna vaccine is authorised for those 18 and older.
As schools are set to reopen for in-person learning in the fall, the issue of vaccinating students is top of mind for parents, teachers and school staff.
Pfiser, which started vaccine trials in children 11 and younger in March, said on its website that it expects to have study results to submit to the FDA for emergency use authorisation for 5 to 11-year-olds in September or October. A Pfiser spokesperson told HuffPost that the company has not provided any further updates to its vaccine trial timelines for children.
Moderna, which also started vaccine trials in children younger than 12 in March, expects to seek emergency authorisation in late 2021 or early 2022, a spokesperson told the Times.
The FDA told HuffPost in a statement that the agency can’t comment on “individual interactions with sponsors” but noted that it works with companies to “ensure the number of participants in clinical trials are of adequate size to enhance the detection of safety signals.”
Moderna did not immediately respond to HuffPost’s request for comment.
In a letter to the editor in the Times earlier this month, the director of the FDA’s centre for Biologics Evaluation and Research, Peter Marks, wrote that the COVID-19 vaccines authorised in the US have been “thoroughly evaluated” and “meet the FDA’s rigorous standards.”
“If we truly want our lives to return to normal, the fastest way to do so is simple,” the FDA director wrote, “get vaccinated right now.”