In a recent announcement from Moderna, they stated their Covid vaccine for children between 6 months to 5 years old is safe. Many parents and pediatricians have been impatiently waiting for a Covid vaccine for the five and under age group (about 19 million children in this age range). The effectiveness of the new shot is a little more complicated, thanks to the emergence of the new omicron variant.

According to their news release, the company stated that the shot met the criteria that they and regulators had determined for success—it generated immune defenses. Children received two shots of a 25-microgram dose, a quarter of the adult dose.

Moderna plans to submit its data to the Food and Drug Administration (FDA) and plan to file for emergency authorization in mid-April. It’s key to note that the data has not been published or peer-reviewed, so regulators must carefully review the details. A panel of outside experts is expected to convene to advise the agency.

The original vaccine trials enrolled tens of thousands of participants and showed, against an earlier version of the virus, the Moderna vaccine was more than 90 percent effective in preventing illness in adults. However, two doses are far less effective against the omicron variant in adults, which holds true for children. The protection against infection was reduced to about 40 percent.

A recent study from the Centers for Disease Control and Prevention (CDC) found that children hospitalization rates soared to the highest level of the pandemic during the winter omicron surge. In January, during the surge’s peak, children younger than five were hospitalized at five times the rate as during the height of the delta surge in early September. Since close to two-thirds of children hospitalized had no underlying medical conditions, there’s no reliable way to predict which ones will end up in the hospital.

Since there were no cases of severe illness or hospitalizations in the 7,000 children who participated in the trial, it can’t be determined if the vaccine can protect against the worst outcomes. Experts say that since children are less prone to severe symptoms from covid, trials would need to be much larger and longer to identify whether the vaccine prevents hospitalization or death.