LOS ANGELES, Aug. 24 (Xinhua) -- The Pfizer-BioNTech COVID-19 vaccine was 73 percent effective in protecting children ages 6 months through 4 years during the time when the Omicron strain was highly prevalent, Pfizer announced Tuesday.

The vaccine was granted Emergency Use Authorization by the U.S. Food and Drug Administration for this age group on June 17.

Participants in the study received either three 3-µg doses of Pfizer-BioNTech vaccine or placebo. Vaccine efficacy was 73.2 percent among children 6 months through 4 years of age without evidence of prior COVID-19 infection, according to the results announced by the two companies.

"While these results confirm that three 3-µg doses of our COVID-19 vaccine provide young children with a high level of protection at a time when the Omicron BA.2 strain was highly prevalent with a favorable safety profile, we are also developing an Omicron BA.4/BA.5-adapted bivalent vaccine in this age group to address these sublineages," said Ugur Sahin, CEO and Co-Founder of BioNTech.