Vaccinating children against COVID-19 will be crucial to ending pandemic, experts say

As the U.S. continues its mass vaccination effort against the coronavirus, experts say getting children inoculated will be crucial to ending the pandemic and ultimately returning to some kind of normalcy.

Children make up about one-fourth of the U.S. population. Estimates for the country to reach "herd immunity," or widespread resistance to the virus, range between 70% to 85% of the population being vaccinated.

The spread of more contagious variants of the virus, which has killed close to 537,000 Americans, has also increased the need for more people to get their shots as soon as possible.

"If children are 25% of the population, you would either have to vaccinate every single last adult or we have to also vaccinate the children," said Dr. Kawsar Talaat, an infectious disease physician and assistant professor with the Johns Hopkins Bloomberg School of Public Health.

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FILE - A third grade student sits during his online class from his social distanced desk on Sept. 3, 2020 in Los Angeles, California. (Photo: Al Seib / Los Angeles Times via Getty Images)

Considering some adults will not be immunized for various reasons, vaccinating the country’s younger population is a needed step to achieving widespread immunity to the virus. Drexel University pediatrics professor Dr. Sarah Long told the Associated Press that immunizing children will be vital to society returning to a time before masks and social distancing.

"It’s unlikely we could get community protection without immunizing children," Long said. "This is the lynchpin to getting everything back to some kind of normalcy."

RELATED: Moderna begins study of COVID-19 vaccine in children under 12

Children develop serious illness or die from COVID-19 at much lower rates than adults, but they do still get sick and can still spread the virus. For Talaat, who has been working on vaccine research for more than a decade and has spent the past year focused specifically on coronavirus vaccines, there are two reasons to vaccinate kids: one being to end the pandemic, and the other for their own protection.

While rates are lower compared to adults, thousands of kids have been hospitalized with the virus over the course of the pandemic. Some have gotten MIS-C, a rare inflammatory syndrome in children linked to COVID-19. More than 260 children have died from the virus.

"That’s a lot of kids," Talaat said of the number of child COVID-19 deaths in the U.S. "(Children) haven’t been able to go to school, they haven’t been able to see their friends. ... In order to get back to where they can be sitting in a classroom full of kids without masks, be seeing their teachers in real life, they need to be vaccinated."

RELATED: NIH launches research effort to understand MIS-C, other effects of COVID-19 on children

Moderna, one of three coronavirus vaccines currently being used in the U.S. for adults, started a study this week of its shot in children under 12 — including babies as young as 6 months.

Both Moderna and Pfizer-BioNTech have completed enrollment for studies of children ages 12 and older and are expected to release the data in the months ahead. Johnson & Johnson, the most recent vaccine to receive an emergency use authorization from the Food and Drug Administration, is beginning to enroll participants in its study for children 12 and up. 

Vaccine researchers started with older children in trials because they tend to respond to the shots most similarly to adults, experts say.

The Pfizer vaccine is already cleared for use starting at age 16, meaning some older kids can get in line for the shot depending on eligibility in their area. The Moderna vaccine is currently cleared for people 18 and older. If the FDA clears the results from ongoing studies, younger teens likewise could start getting vaccinated as supply allows.

President Joe Biden has directed U.S. states to make all adults eligible for the vaccine by May 1 amid an increase in vaccine supply from all three developers — though the process of actually administering the doses will take time.

More than 110 million coronavirus vaccines have been administered across the country. As of this week, roughly 27% of U.S. adults have received their first shot and 15% are now fully vaccinated, according to Andy Slavitt, White House senior advisor for COVID response.

Dr. Anthony Fauci, the government’s top infectious disease expert, has estimated that high school-age children could get vaccinated in the fall.

Talaat, who does work in both COVID-19 vaccine clinical trials as well as vaccine safety, said she anticipates vaccines becoming available for older kids even sooner — possibly by early summer. She noted that these trials are already fully enrolled and are focused on the safety and immune responses of the shots within this age group. But first, the U.S. must finish vaccinating priority groups, such as those with underlying conditions.

"The thing about vaccines, or authorized for older children is, they’re not really a priority group," Talaat explained. "So until those people are vaccinated and we’re in the general population of healthy young adults who have no risk factors, then we’re not going to be vaccinating teenagers because they’re generally not high risk."

Talaat said she anticipates seeing the first vaccines becoming available for younger children potentially by "late fall." Fauci also recently said children under age 12 will likely be able to get vaccinated at the end of 2021 or "very likely the first quarter of 2022."

This story was reported from Cincinnati.