A nurse fills a syringe with Pfizer vaccine as mobile vaccination teams begin visiting every Los Angeles Unified middle and high school campus to deliver first and second doses of the coronavirus disease (COVID-19) vaccines in Los Angeles, California, U.S., August 30, 2021. REUTERS/Mike Blake Top U.S. health officials believe that Pfizer Inc’s (PFE.N) COVID-19 vaccine could be authorized for children aged 5-11 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 (22UAy.DE), 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) towards 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.