March 11, 2022
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The Pfizer-BioNTech COVID-19 vaccine reduced the risk of infection with the omicron variant of SARS-CoV-2 by 31% among children aged 5 to 11 years and 59% among adolescents aged 12 to 15 years, according to data published Friday in MMWR.
The real world study also found that the vaccine was 87% effective against infection with the delta variant among adolescents. The variant increased before younger children had access to the vaccine.
“Real-world data on vaccine efficacy (RE) are needed in these age groups, especially because when omicron variant became prevalent in the United States in December 2021, early studies of RE showed a decrease in protection against symptomatic infection for adolescents aged 12-15 years and adults, “CDC COVID-19 Emergency Response Team Member Ashley L. Fowlkes, ScD, and colleagues wrote.
In a statement, the CDC noted this data published last week showed that the efficacy of the vaccine against COVID-19-associated hospitalization ranged from 92% to 94% among adolescents aged 12 to 17 years during delta elevation to 74% in children aged 5 to 11 years during omicron elevation.
The new study “reinforces the importance of vaccination to keep children and adolescents protected from serious illness and out of the hospital.”
“COVID-19 vaccination remains a safe and critical tool for protecting children and teens regardless of their state of health,” the CDC said.
Fowlkes and colleagues analyzed data from PROTECT, a prospective cohort study monitoring SARS-CoV-2 infections among participants aged 6 months to 17 years in four states of Arizona, Florida, Texas and Utah.
The study included 1,364 participants – 1,052 children aged 5 to 11 years and 312 adolescents aged 12 to 15 years – who were tested at least weekly between July 25, 2021 and February 12, 2022. Most of the participants lived in Arizona.
Among the younger age group, the efficacy of two doses of the vaccine was 31% (95% CI, 9% -48%) when adjusted for sociodemographic characteristics, health information, frequency of social contact, mask use, location, and local viral circulation. , reported Fowlkes and colleagues. Among adolescents aged 12 to 15 years, it was 87% (95% CI, 49% -97%) against symptomatic and asymptomatic delta infection and 59% (95% CI, 22% -79%) against omicron infection.
The researchers also reported that among unvaccinated participants with SARS-CoV-2 infection, those infected with the delta variant were more likely to report COVID-19 symptoms (66%) than those with omicron infections (49%). ).