More than half a year has passed since the first vaccine for COVID-19 and almost half the US has protection against the SARS-CoV-2 virus. But there still isn’t one for children younger than 12.

Vaccine makers have been working to make their products available to younger patients, launching clinical trials to evaluate whether the vaccines can safely and effectively protect children as young as 6 months.

One site for those trials is at Children’s Hospital of Philadelphia (CHOP), where Jeff Gerber, a pediatrician, epidemiologist, and infectious disease specialist, is heading Moderna’s effort.

Here, Gerber talks about how the vaccines are being adapted for kids, what special considerations go into a pediatric clinical trial, and why giving children access to a COVID-19 vaccine is critical for their health— mentally, emotionally, and physically:

Can you describe what the trial aims to do and its progress to date?

This is the KidCOVE trial, which is testing the Moderna mRNA COVID-19 vaccine in kids from 6 months up until just before they turn 12. Moderna conducted a study for 12 to 17-year-olds that’s under review right now.

KidCOVE, like many of the COVID vaccine trials, is co-led by the National Institutes of Health and industry.

This is a combination phase 2/3 trial. These two parts can be done in direct sequence because this vaccine has already been tested extensively in adults and older children and has lots of safety and effectiveness data.

Phase 2 is what is called the dose finding and age de-escalation portion. They divide the participants into three subcategories: 6-11 years, 2-5 years, and then six months to just under 2. In each of those age categories, the trial starts out by giving a lower dose than what the teenagers and adults get and testing a small number of children to look at safety and immune response.

If all looks good, then they will increase the dose a bit, doing it very carefully by starting with the older age group then moving down, looking at side effects. Phase 2 will finish once they decide they have a dose for each age group with a favorable side effect profile and strong immune response, and that is the dose that will be tested in phase 3. That is a randomized controlled trial, where the vaccine is tested against a placebo. It’s possible that one age group might move into phase 3 ahead of the others.

This trial is spread across up to 80 sites, mostly in the US. CHOP is just one of them. The overall trial will include approximately 7,000 kids, the majority of which will be in the randomized controlled trial. Our expectation at CHOP is to enroll somewhere around 100 subjects.

Read the full article about the COVID-19 vaccine for kids by Katherine Unger Baillie at Futurity.