Johnson & Johnson is likely to have a COVID-19 vaccine available for children under the age of 18 by September, says CEO Alex Gorsky.

“I think it’s likely to occur right in that timeline. The good news is, is that the FDA is already working with companies to establish the clear regulatory guidelines, so that the appropriate data can be collected,” Gorsky told David Ignatius during a Washington Post Live event on Wednesday

Gorksy said one benefit of the Johnson & Johnson vaccine is that this particular type of vaccine has been used in lower age groups before.

“The AdVac 26 was used extensively among broad age groups, young and old in Africa when we were developing this for other conditions such as Ebola and HIV. So it gives us reasons to be optimistic regarding the safety profile in that in that patient population, but we still have to do the clinical work,” he said.

Johnson & Johnson first announced their plans last week to study the vaccine in adolescents. Gorsky says it will begin testing in people ages 12 to 18, and it will go down from there.

“We will conduct several immunogenicity and safety studies in children from 17 years of age down to neonates,” Dr. Macaya Douoguih, head of clinical development & medical affairs with J&J’s vaccine arm Janssen, told a Centers for Disease Control and Prevention advisory committee last week.

“We are also anticipating a study in pregnant women in the second and third trimesters toward the end of March, early April,” Douoguih said. “We also plan to begin a study in immunocompromised individuals in the third quarter of this year.”