US biotech firm Moderna said Thursday it had submitted a request for an emergency use authorization in the United States for its Covid vaccine for children aged six months to under six years.
Children under six are the only age group that has yet to gain access to a Covid-19 vaccine in the United States and in most countries.
"We believe (this vaccine) will be able to safely protect these children against SARS-CoV-2, which is so important in our continued fight against Covid-19 and will be especially welcomed by parents and caregivers," the company's CEO Stephane Bancel said in a statement.
In March, the company announced results from a trial that showed the two-shot regimen was found to be safe and produced a strong immune response.
Specifically, two doses of 25 micrograms given to babies, toddlers and preschoolers generated similar levels of antibodies as two doses of 100 micrograms given to young people aged 18-25, indicating there would be similar levels of protection against serious cases of the virus.
The trial included 4,200 children aged two to six years and 2,500 babies aged six months to two years.
Side effects were generally mild and consistent with those seen in older age groups
The company did, however, find relatively low efficacy against infection, with its trial taking place during the Omicron variant wave.
The current generation of vaccines were designed against the original strain of the virus.
Vaccine efficacy in children six months up to age two was 51 percent, and efficacy was 37 percent in the two to five years age group, when limiting the analysis to only cases confirmed positive on a positive PCR test.
Moderna said these were similar to vaccine efficacy estimates in adults during Omicron, and it is also currently studying booster doses for all pediatric cohorts.
The lower efficacy for two doses has the potential to present a stumbling block to authorization.
Back in February, the Food and Drug Administration (FDA) postponed a meeting of a panel to consider the Pfizer-BioNTech Covid vaccine for children younger than five, saying it wanted to see data on how three doses performed before considering the matter.
The companies said at the time they expected that data to be ready in April, but haven't provided an update since then.
Scientists evaluating a vaccine for infants must closely consider the risk-benefit balance.
Even when they are unvaccinated, children under five are at very low risk for severe disease. There have been only 476 deaths in the United States this age group since the start of the pandemic, according to official data.
Among all US children, there have also been almost 8,000 cases of MIS-C, a post-viral inflammatory condition, that caused 66 deaths.