Pfizer-BioNTech officials announced Thursday (October 7) they are seeking emergency use authorization by the U.S. Food and Drug Administration for their COVID-19 vaccine in children ages 5 to 11, CNN reports.

The companies initially submitted data to the FDA in an effort to be granted approval for use of the vaccine nine days prior, but hadn't formally requested authorization.

The vaccine would become the first authorized for use in younger children after previously being approved for individuals 16 and older and being granted emergency use approval for ages 12 to 15.

On September 28, NBC News reported the FDA was expected to take "at least several weeks" to analyze the data submitted by the company during recent trials -- which included more than 2,000 children participating -- before reaching a decision on granting emergency use authorization.

Officials for Pfizer-BioNTech said a formal submission to request emergency use authorization of the vaccine in children ages 5 to 11 is expected to follow during the upcoming weeks.

"The FDA takes very seriously the importance of getting vaccines, shown to be safe and effective in children," said Dr. Anthony Fauci, the director of the National Institute of Allergy and chief medical advisor to President Joe Biden, via MSNBC's Morning Joe show. "I would imagine in the next few weeks they will examine that data and hopefully give the O.K. so we can start vaccinating children hopefully by the end of October."

The Pfizer vaccine has already been available for ages 12 and older since May, but millions of younger children are still vulnerable to COVID-19 as schools recently returned to in-person instruction with varying mask requirements.

Pfizer reported its two-dose COVID vaccine showed safe results, with a "well tolerated" and "robust" antibody response among the younger children who participated in its recent trials.

The children were given two smaller doses of the vaccine than previously distributed to ages 12 and older, which produced comparable antibody responses to results from its study among people ages 16 to 25 who received full doses.

The recent vaccine trials also resulted in similar side effects to previous trials among adults, which included arm soreness and fatigue among partipants.