Drugmaker Pfizer has plans to start testing its experimental coronavirus vaccine in children as young as 12, and parents have already expressed interest in enrolling their kids, the researcher leading the trial told CNN Tuesday.

It will be the first coronavirus vaccine trial to include children in the United States.

A team at Cincinnati Children's Hospital will begin vaccinating teenagers aged 16 and 17 this week, and will move to enroll 12-to 15-year-olds later, said Dr. Robert Frenck, director of the Vaccine Research Center at the hospital.

The company confirmed on its website it has approval from the U.S. Food and Drug Administration to enroll children as young as 12 in its trial.

"We really think a vaccine for adolescents and children is going to be critical for getting Covid under control," Frenck told CNN in a telephone interview.

"I think one of the things that is important to remember is that although the death rate for children with Covid is lower than in older adults, it's not zero," he saId, noting that more than half a million children have been diagnosed with coronavirus in the U.S. "It is not a nonexistent infection in children."

Children can develop serious illness and also die from coronavirus and there is no way to predict which ones will, he said. They also can spread it to other, more vulnerable people, including parents, grandparents, healthcare workers and others. And children can develop a rare but serious side-effect from coronavirus infection called multisystem inflammatory syndrome in children or MIS-C.

Frenck also believes more children have been infected with coronavirus than the official data show. "I think we are probably under detecting the number of kids that are infected because they are not getting sick enough to where a parent says they need to go to a doctor," he said.

"Most of the time in kids, you have a young kid at home and they have a runny nose, they have a cough -- you are not going to bring them to a doctor," he added.

"And most of the time, what a coronavirus causes is a cold."

Plus, the FDA has asked the companies working to make a coronavirus vaccine to test them in diverse groups -- including in people usually missed in drug and vaccine trials, such as the elderly, Blacks, Hispanics and Native Americans.

Pfizer, one of four companies to have vaccines in advanced, Phase 3 clinical trials in the U.S., says it has enrolled close to 38,000 volunteers in its trial. More than 31,000 of them have received the second of two shots.

Frenck said more than 90 people have responded to an ad looking for volunteers to sign up teens for the trial.

Pfizer developed its two-dose coronavirus vaccine with Germany's BioNtech. It uses pieces of viral genetic material to induce immunity to the coronavirus.

"If regulatory approval or authorization is obtained, the companies expect to manufacture globally up to 100 million doses by the end of 2020 and potentially 1.3 billion doses by the end of 2021," the company said on its website.