COVID-19 vaccine strongly effective for children and adolescents during delta and omicron

Children and adolescents who received one of the main COVID-19 vaccines were significantly protected from the illness and showed no increased signs of cardiac complications compared to young people who were not vaccinated, according to a new real-world study led by researchers from the Perelman School of Medicine at the University of Pennsylvania and Children’s Hospital of Philadelphia (CHOP).

When the Delta variant rose to prominence, the study showed that vaccinated young people were 98 percent less likely to be infected than their unvaccinated peers, and data indicated that the vaccine’s effectiveness decline slightly when the Omicron variant became dominant. The paper was published in Annals of Internal Medicine.

In their analysis of 250,000 patients with around half of them received at least one dose of the BNT162b2 vaccine (the vaccine produced by a collaboration between Pfizer and BioNTech), the researchers—led by Yong Chen, PhD, and team the periods in which the Delta and Omicron variants became dominant, in mid-2021 and 2022, respectively.

“Our study has longer follow-up than any previous study, which enabled us to evaluate the real-world, long-term durability of vaccine protection against Delta and Omicron variants,” said Chen. “Further, it covered a diverse representation of U.S. pediatric populations from primary care, specialty care, emergency department, testing centers, and inpatient settings.”

One of the main ideas behind the work, as stated by the study’s first authors—Qiong Wu, PhD, a postdoctoral research fellow at Penn Medicine and Jiayi Tong, a PhD candidate in Biostatistics at Penn—was to help address under-reporting in vaccine status to give a clearer picture of its effects.

Yet, infection prevention wasn’t the study’s only area of focus. The researchers also explored potential effects on risk of heart conditions.

“We found no indication of increased cardiac risks during either variant phase,” said Morris.

Reference: Real-world analysis: COVID-19 vaccine strongly effective for children and adolescents during delta an omicron; Annals of Internal Medicine