The Pfizer/BioNTech COVID-19 vaccine has been found to be 93% effective in preventing hospitalizations due to the disease in children between 12 and 18 years of age in a study by the US Centers for Disease Control and Prevention (CDC). 

There was only a slight variation in vaccine effectiveness within that age group, with 91% effectiveness seen for 12 to 15 years age group and 94% effectiveness for those ages 16 to 18 years. The study included 464 patients, with 179 hospitalized with COVID-19 and 285 hospitalized due to other causes. Around 72% of patients had at least one underlying medical condition and 68% attended in-person school. Of the 179 patients hospitalized due to COVID, 97% had not received their vaccination. All of the critically ill patients were unvaccinated - about 77 patients were admitted to an intensive care unit, 29 received life support and two died… (CNN, October 19, 2021)