Moderna’s COVID-19 vaccine works in babies, toddlers and preschoolers, the company announced Wednesday – a development that could pave the way for the littlest kids to be vaccinated by summer if regulators agree.

Moderna said that in the coming weeks it would ask regulators in the U.S. and Europe to authorize two small-dose shots for youngsters under 6. The company also is seeking to have larger doses cleared for older children and teens in the U.S.

The announcement is positive news for parents who have anxiously awaited protection for younger tots and been continuously disappointed by setbacks and confusion over which shots might work and when. The nation’s 18 million children under 5 are the only age group not yet eligible for vaccination.

Moderna says early study results show tots develop high levels of virus-fighting antibodies from shots containing a quarter of the dose given to adults. Once Moderna submits its full data, the U.S. Food and Drug Administration will have to determine if that important marker means the youngsters are as protected against severe illness as adults.

“The vaccine provides the same level of protection against COVID in young kids as it does in adults. We think that’s good news,” Dr. Stephen Hoge, Moderna’s president, told The Associated Press.

But that key antibody finding isn’t the whole story. COVID-19 vaccines aren’t as effective against the super-contagious omicron mutant – in people of any age – and Moderna’s study found the same trend. There were no severe illnesses during the trial but the vaccine was only about 44% effective at preventing milder infections in babies up to age 2, and nearly 38% effective in the preschoolers.

“Not a home run” but the shots still could be helpful for the youngest children, said Dr. Jesse Goodman of Georgetown University, a former FDA vaccine chief. Goodman said the high antibody levels seen in the study “should translate into higher efficacy against severe infections.”

Some parents say even a little protection would be better than leaving their youngest children unvaccinated.