Studies confirm COVID-19 vaccine’s effectiveness in teens, even against Delta

When the U.S. Food and Drug Administration authorized the first COVID-19 vaccine for use in adolescents as young as 12, regulators based their decision on clinical trial data collected before the Delta variant became the dominant coronavirus strain. This left the question open as to whether the vaccine was as effective in real-world protection as it claimed. Two new studies offer strong support for the assertion that the vaccine is safe.

Even when confronted by the highly transmissible Delta variant, the vaccine made by Pfizer-BioNTech greatly reduced the risk of coronavirus infection, COVID-19 illness and hospitalization among teens.

The results of this study show that it is “imperative” for shots to be given to unvaccinated teens across the U.S. One of the research teams published Tuesday’s a study by the Centers for Disease Control and Prevention .. As of Monday, 54% of Americans ages 12 to 15 and 46% of those ages 16 or 17 were not fully vaccinated against COVID-19, they noted.

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The study, which appeared in the CDC’s Morbidity and Mortality Weekly Report, examined data from 19 pediatric hospitals in 16 states. Researchers compared 179 patients who were treated for COVID-19 and 285 patients from the same hospitals who were treated for other conditions.

All the patients were between the ages of 12 and 18, and they were admitted between June 1 and Sept. 30, when the Delta variant was responsible for most coronavirus infections in the U.S.

Among the 179 patients with COVID-19, only six — or 3% — had received both doses of the Pfizer-BioNTech vaccine at least 14 days before they came to the hospital. The remaining 97% of COVID-19 patients were unvaccinated. The study did not include teens who had been partially vaccinated. )

By comparison, among the 285 patients in the control group, 93 — or 33% — were fully vaccinated against COVID-19, and the remaining 67% were unvaccinated.

By comparing those two groups, the researchers calculated that the Pfizer-BioNTech vaccine was 93% effective at preventing COVID-19 hospitalizations among adolescents, even in the Delta era.

The vaccine appeared to do an even better job of preventing the most critical cases of COVID-19. Among the patients with the disease, 77 had to be admitted to the intensive care unit, including 29 who required mechanical ventilation or other life-support interventions. Two of these patients succumbed to the disease.

None of the 77 patients who were treated in the ICU had been vaccinated.

The study “reinforces the importance of vaccination to protect U.S. youths against severe COVID-19,” the authors wrote.

The second study focused on the vaccine’s ability to reduce the risk of coronavirus infection and cases of COVID-19, including illnesses with only mild symptoms. It was based on records of 94,354 adolescents in Israel who received the Pfizer-BioNTech vaccine between June 8 and Sept. 14, along with records of 94,354 other teens who were matched on the basis of demographic and health data but were not vaccinated for COVID-19.

All the participants were between the ages of 12 and 18, and none had experienced a known coronavirus infection prior to joining the study. The Delta variant accounted for more than 95% of new cases in Israel during the study period, the researchers noted.

The vaccinated adolescents were tested for active coronavirus infections at a rate of 9.4 tests per 100 people per week. That was slightly less than the 9.9 tests per 100 people per week among the unvaccinated teens, but it was similar enough that any difference in infection rates couldn’t be attributed to the fact that one group was tested more frequently than the other. The vaccine worked better in teens who received both doses. It was also more effective in reducing the risk of developing a confirmed coronavirus infection.

One to three weeks after the second dose, the vaccine was 90% effective at reducing the risk of a confirmed coronavirus infection and 93% effective at reducing the risk of COVID-19, the study authors calculated. These figures were “similar” in nature to the vaccine’s effectiveness against illnesses and infections caused by the Alpha variant of the United Kingdom. The findings from Israel were published in Wednesday’s New England Journal of Medicine.

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