Pfizer announced Wednesday that it has begun clinical trials of its COVID-19 pills in children ages 6 to 17. 

Children are less likely than adults to become severely ill from COVID-19, but, according to CDC data, Americans ages 0 to 18 years have accounted for more than 1,000 deaths during the pandemic, and over 115,000 kids have been hospitalized by the virus in the last seven months alone.

If approved by regulators, the oral treatment, called Paxlovid, would be used for nonhospitalized, symptomatic pediatric patients who are at risk of developing severe disease. 

In December, the Food and Drug Administration authorized the pill for emergency use in adults, as well as in children who are 12 or older and weigh at least 88 pounds. The safety and efficacy of the medication in patients younger than 18 had not yet been established, but scientific modeling suggested the treatment would have comparable results to what was seen in adults.

Pfizer’s clinical trial for adults found the pill was 89% effective against hospitalization and death when taken within three days of developing symptoms, and 88% effective within five days.

There were no deaths reported in the treatment group, and the reported side effect were mild and comparable with the placebo group.

“There is a significant unmet need for outpatient treatments that can be taken by children and adolescents to help prevent progression to severe illness, including hospitalization or death,” Mikael Dolsten, Pfizer’s chief scientific officer, said in a news release. “ … We are proud to expand studies of our novel COVID-19 treatment to include pediatric participants to further evaluate the safety and efficacy of this treatment in this important population.”

A single adult dosage of Paxlovid is actually three pills: two 150-milligram tablets of nirmatrelvir and one 100-mg tablet of ritonavir. Nirmatrelvir is designed to block an enzyme the coronavirus needs to replicate, while the ritonavir helps slow the breakdown of nirmatrelvir so that it can remain active in the body longer. 

Pfizer said the kids’ trial will include 140 patients divided into two groups — one for those weighing at least 88 pounds, the other for those weighing 44-88 pounds. The heavier group will be receive the same dosage given to adults, while the lighter group will be given a lower dosage — just one 150-mg nirmatrelvir pill and one 100-mg ritonavir pill. The trial participants will take the medication twice a day for five days. 

Pfizer said it also is working on developing an age-appropriate version of the treatment for children younger than 6. The drugmaker says it will begin that clinical trial as data from the older kids become available.