Top U.S. health officials believe that Pfizer Inc.'s COVID-19 vaccine could be authorized for children aged 5- to 11-years-old by the end of October, two sources familiar with the situation said on Friday.

The timeline is based on the expectation that Pfizer, which developed the shot with Germany's BioNTech, will have enough data from clinical trials to seek emergency use authorization (EUA) for that age group from the U.S. Food and Drug Administration (FDA) toward the end of this month, the sources said.

They anticipate the FDA could make a decision on whether the shot is safe and effective in younger children within three weeks of the EUA submission.