Pfizer-BioNTech is testing a 3-dose vaccine for 2-5 year olds after data showed the 2-dose mRNA vaccines were ineffective in that age group.
The extended research will delay mRNA vaccines for 2-5 year olds until 2022, Pfizer said in a statement on Friday.
The announcement means Pfizer won’t have to present data to regulators until the first half of 2022, NBC News reports.
Earlier this month, Pfizer CEO Albert Bourla, a Greek veterinarian, said the company would have data on 2-5 year olds by the end of the year.
In a news release on Friday, Pfizer said two doses generated a strong immune response in children under 2, but not in children ages 2 to under 5.
“We have decided to modify each of the pediatric studies to incorporate a third dose to the series and seek licensure for a three-dose series rather than a two-dose series as originally anticipated,” Kathrin Jansen, Pfizer’s head of vaccine research, said on a conference call with investors on Friday.