On March 4, 2022, the Centers for Disease Control and Prevention (CDC) published a study reporting on the effectiveness of the Pfizer-BioNTech COVID-19 vaccine in children and adolescents 5-17 years old. In previously conducted clinical trials, which included children and adolescents ages 5-17, the efficacy of the vaccine against laboratory-confirmed COVID-19 was greater than 90%. A lack of real-world data on overall vaccine effectiveness and effectiveness against the Omicron variant prompted a need for this study, in which the CDC examined 39,217 emergency department (ED) and urgent care (UC) encounters, and 1,699 hospitalizations of patients ages 5-17. The full study included the pre-Delta, Delta and Omicron predominant periods. Among adolescents ages 12-17, vaccine efficacy estimates were highest (76-83%) at 14-149 days after completion of the 2-dose vaccination series. Vaccine efficacy dropped significantly (38-46%) at 150 days after completion of the vaccination series. Administration of a third, booster dose, increased vaccine efficacy to 86% amongst adolescents ages 16-17. Children ages 5-11 experienced significantly lower vaccine efficacy (46%) when compared to those ages 12-17 but most encounters included in the study for children 5-11 occurred during the period dominated by the Omicron variant. When only comparing the Omicron variant, the efficacy rates were comparable to those seen in the adolescent groups ages 12-15 and 16-17, 45% and 34%, respectively. These study results are consistent with previous studies which found that vaccine efficacy among adults was lower during Omicron variant predominance, with an increase in efficacy upon administration of a third, booster dose. It is important to note that the difference in vaccine efficacy among the different age groups can be attributed to the timing of vaccine availability. The results of this study provide real-world evidence supporting the CDC recommendation that all children and adolescents remain up to date with the recommended COVID-19 vaccinations. The Pfizer-BioNTech vaccine is currently FDA approved for use in anyone age 5 and older, with a third booster dose approved for those over age 12.