Moderna says it plans to expand the size of its COVID-19 vaccine study in younger children to better detect rare side effects, such as a type of heart inflammation recently flagged by health authorities in the United States.
The company says it is in talks with the Food and Drug Administration to enroll more study participants under age 12.
It had intended to test the vaccine in about 7,000 children, with some as young as six months.
The Cambridge, Massachusetts-based company said via email it hasn’t decided on how many kids might be added.
Regulators continue to review cases of a rare type of heart inflammation called myocarditis that has been reported in a small number of teenagers who got the Moderna or Pfizer shots.
Pfizer said today if it makes changes to its vaccine testing in children, it will provide an update then.
The New York-based company is testing its vaccine in up to 45-hundred children in the United States and Europe.
The Food and Drug Administration said in a statement it could not comment on its discussions with companies, but added that “we do generally work with sponsors to ensure the number of participants in clinical trials are of adequate size to detect safety signals.”
US officials and independent medical experts said last month the benefits of the vaccines far outweigh the risks of the side effect, which has been reported in several hundred people younger than 30.
But any vaccine safety issues could slow uptake, particularly among parents wary of taking any health risk with their children.
Currently, Pfizer is the only vaccine in the United States and Canada to be authorized for children 12 years and up. Moderna is expecting an FDA ruling on its application in the coming days. The company has filed a similar application with Health Canada.
Earlier this month, the European Medicines Agency recommended authorizing Moderna’s COVID-19 vaccine for children ages 12 to 17, the first time the shot has been authorized for people under 18.
The EU drug regulator said research in more than 3,700 children aged 12 to 17 showed that the Moderna vaccine – already given the OK for adults across Europe – produced a comparable antibody response.
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