US biotech firm Moderna on Wednesday said it was pursuing regulatory approval for its Covid vaccine in children aged six months to six years after the two-shot regimen was found to be safe and produced a strong immune response.

Specifically, two doses of 25 micrograms given to this age group generated similar levels of antibodies to two doses of 100 micrograms given to young people aged 18-25, indicating there would be similar levels of protection.

Based on the data, Moderna said it would submit authorization requests to the US Food and Drug Administration (FDA), European Medicines Agency (EMA) and other global regulators in the coming weeks.

The results "are good news for parents of children under six years of age," said CEO Stephane Bancel in a statement. 

"We now have clinical data on the performance of our vaccine from infants six months of age through older adults."

The company did however find relatively low vaccine efficacy against infection, with its trial taking place during the Omicron wave.

Vaccine efficacy in children six months to two years was 43.7 percent, and vaccine efficacy was 37.5 percent in the two to under six years age group. 

Moderna said this was consistent with what had been observed among adults and the company was evaluating a third dose to lift efficacy levels.

The trial comprised 11,700 pediatric volunteers in the United States and Canada, including 4,200 aged two to six years and 2,500 aged six to two months.

The company added that, after consulting with the FDA, it is also applying to be authorized among children six to 11 for two-doses of 50 micrograms, and updating its application for authorization in kids aged 12 through 17. 

The EMA and other regulators have already authorized the Moderna vaccine in these age groups.

Last month, the FDA postponed a meeting of a panel to consider the Pfizer-BioNTech Covid vaccine for children younger than five, saying it required additional data on third doses. The companies said they expected that data to be ready by April.