The U.S. Food and Drug Administration (FDA) on Monday approved Pfizer's (PFE  ) and BioNTech's (BNTX  ) request to allow adolescents between the ages of 12 and 15 to receive the companies' COVID vaccine on an emergency use basis. This decision follows a more than 2,000 participant study that demonstrated that the vaccine was 100% effective in that age group.

The two-dose vaccine regimen has been authorized for emergency use in individuals age 16 and older in the United States since Dec. 11, 2020. The U.S. Centers for Disease Control and Prevention's (CDC) vaccine advisory committee is scheduled to meet on Wednesday to review the vaccine's potential use in adolescents. If approved, as it is expected to be, the U.S. could start administering to younger Americans as soon as possible.

"Having a vaccine authorized for a younger population is a critical step in continuing to lessen the immense public health burden caused by the COVID-19 pandemic," said Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, in a statement.

From March 1, 2020 through April 30, 2021, approximately 1.5 million COVID-19 cases in individuals between the ages of 11 and 17 were reported to the CDC. While children and adolescents are less likely to develop severe COVID infection--or any symptoms at all--they can still spread the virus to more vulnerable populations.

"This is exciting news," U.S. National Institutes of Health Director Dr. Francis Collins told CNBC, describing the FDA's decision as "a big deal" in the nation's fight against the pandemic. "We know that a million-and-a-half adolescents have been infected with COVID-19 since this pandemic stated, and not all of them have fared as well as most. And some of them have ended up with this ong COVID where they're not better, even weeks or months after getting ill, so we really want to protect adolescents."

The Biden administration has focused on vaccinating adolescents as part of President Joe Biden's plan to fully vaccinate 160 million Americans by July 4; Independence Day is a date that the White House expects to be a turning point towards a sense of normalcy for the nation.

Children under the age of 18 make up about 20% of the total U.S. population, according to U.S. government data.