Moderna said on Sunday (Oct 31) it has been told that the US Food and Drug Administration will require additional time to complete its assessment of the company's COVID-19 vaccine for use in adolescents aged 12 to 17 years.
The FDA informed Moderna that the review may not be completed before January 2022, the company said in a statement, dealing a potential setback to the timing of an emergency use authorisation (EUA) for that age group.
Moderna Chief Executive Stephane Bancel told Reuters last week that based on conversations with the agency, he believed the vaccine would be authorised for those 12 to 17 in the next few weeks.
The US biotech company said it was told late on Friday that the FDA needed the additional time to evaluate recent international analyses of the risk of a type of heart inflammation called myocarditis after vaccination, a rare side effect that has primarily affected young males.
Moderna said it is conducting its own review of new external analyses on the increased myocarditis risk in those less than 18 years of age as they become available.
Moderna applied for US authorisation of its shot for those aged 12 to 17 in June.
Americans of those ages are eligible for the similar COVID-19 vaccine from Pfizer and partner BioNTech after it was cleared by the FDA and Centers for Disease Control and Prevention in May.
Moderna also said it will delay filing its request for an EUA for a half strength 50-microgramme dose of the vaccine for children ages 6 to 11 while the FDA completes its review of the 12-17 filing.