Pfizer Inc.’s COVID-19 vaccine was 73.2% effective against the disease in a trial of children 6 months through 4 years old, reinforcing results that led to the shot’s authorization in young kids in June.

The three-dose regimen was compared with placebo injections during the period when omicron’s BA.2 version was spreading widely from March to June, Pfizer and partner BioNTech SE said Tuesday in a statement. There were 13 cases in the vaccinated group and 21 in the placebo group, the statement said.

Pfizer and BioNTech’s messenger RNA vaccine was authorized for use in young children based on results that showed it generated a similar immune response to one that was seen as protective in adults. When regulators authorized the shots, they said that Pfizer's effectiveness data in young children were not yet mature.

The companies plan to submit the updated data to the U.S. Food and Drug Administration, the European Medicines Agency and other regulators in the coming weeks. They are also developing a vaccine that will target the BA.4 and BA.5 omicron strains that are spreading widely now, according to the statement.

Rival Moderna Inc. makes a vaccine for young children that’s administered in two shots. That shot was 51% effective at preventing cases of COVID for those under 2 years and 37% effective for those ages 2 to 5.

Pfizer shares and BioNTech’s American depositary receipts were little changed in trading before US markets opened.