Two Doses of Pfizer-BioNTech Prove Highly Effective at Preventing COVID-19 Hospitalizations in Adolescents

There is a heavy focus on how COVID-19 causes higher rates of severe disease and mortality in older adults, but there is limited data on the real-world efficacy of vaccines in adolescents (12-18 years of age).

New research released today by the Centers for Disease Control and Prevention (CDC) examined the effectiveness of 2 doses of the mRNA Pfizer-BioNTech vaccine against hospitalizations in 12-18-year-olds.

The study ran from June-September 2021, and investigators included 464 fully vaccinated (with Pfizer-BioNTech) or fully unvaccinated patients (having received no doses of any COVID-19 vaccine) in 19 pediatric hospitals. Of these, 179 were case-patients and 285 were controls. According to the CDC’s Morbidity and Mortality Weekly Report, “Case-patients were hospitalized with symptomatic COVID-19–like illness and a positive SARS-CoV-2 reverse transcription–polymerase chain reaction (RT-PCR) or antigen test result; no case-patients received a diagnosis of multisystem inflammatory syndrome in children (MIS-C) during their enrolling hospitalization. Two hospitalized control groups were enrolled: 1) patients with symptoms compatible with COVID-19 with negative SARS-CoV-2 RT-PCR or antigen test results (test-negative) and 2) patients without COVID-19–associated symptoms who might or might not have received SARS-CoV-2 testing (syndrome-negative).”

The median age of the case-patients and controls was 15 years, 72% had at least one underlying condition, and 68% attended school in-person. The average length of hospital stay was 5 days among unvaccinated patents and 3 days for vaccinated patients.

Among the 179 case-patients, 6 (3%) were vaccinated and 173 (97%) were unvaccinated. 77 (43%) case-patients were admitted to the intensive care unit (ICU), 29 (16%) became critically ill, and 2 (7%) died. All case-patients who were admitted to the ICU, became critically ill, and died were unvaccinated.

Among the hospitalized 12–18-year-olds, 97% were unvaccinated. This confirms the importance of vaccinations and disproves prior assumptions that children, adolescents, and young adults could not become severely ill upon contracting COVID-19.

All patients studied were hospitalized in this real-world analysis, and full vaccination reduced the risk of hospitalization of persons 12-18 years old by 93%. Notably, this study was conducted while Delta (B.1.617.2) was the predominant variant, proving the Pfizer-BioNTech vaccine remained effective even against this more infectious strain. These results were consistent with other studies conducted by Pfizer-BioNTech and other unaffiliated researchers.

The CDC expressed confidence in the success of vaccinating adolescents, and is expected to move on approving vaccinations for even younger children.