Pfizer announced Wednesday that its COVID-19 vaccine is safe and strongly protective in kids as young as 12, a step toward possibly beginning shots in this age group before they head back to school in the fall. Most COVID-19 vaccines being rolled out worldwide are for adults, who are at higher risk from the coronavirus. Pfizer’s vaccine is authorized for ages 16 and older. In a study of 2,260 U.S. volunteers ages 12 to 15, preliminary data showed there were no cases of COVID-19 among fully vaccinated adolescents compared to 18 among those given dummy shots, Pfizer reported. It’s a small study, that hasn’t yet been published, however researchers reported high levels of virus-fighting antibodies, somewhat higher than were seen in studies of young adults. Kids had side effects similar to young adults, the company said. The main side effects are pain, fever, chills, and fatigue, particularly after the second …