Federal health regulators said late Friday that kid-size doses of Pfizer's COVID-19 vaccine appear highly effective at preventing symptomatic infections in elementary school children and caused no unexpected safety issues, as the U.S. weighs beginning vaccinations in youngsters. The FDA posted its analysis of Pfizer's data ahead of a public meeting next week to debate whether the shots are ready for the nation's roughly 28 million children ages 5 to 11. The agency will ask a panel of outside vaccine experts to vote on that question.