Pfizer and BioNTech reported positive results for a third dose of their COVID-19 vaccine indicating its efficacy in children under five years old.

The clinical trial, which enrolled 1,678 children, administered a third dose at least two months after the second dose. The study was conducted at a time when Omicron was the dominant variant.

Comirnaty was 80.3 percent effective at preventing symptomatic infection in participants who were between six months old and under five years old. Comirnaty had a favorable safety profile that was comparable to placebo, the companies said.

Pfizer and BioNTech began a rolling submission to the FDA for Emergency Use Authorization (EUA) in February for children between six months old and under five years old. They are expected to complete the EUA submission for this patient population this week.