Israeli Study: COVID Vaccine Is 90% Effective at Reducing Delta Infection Among Teens

Ido Efrati
Ido Efrati
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Teenager in a Pink Floyd T-shirt receiving the COVID vaccine
Teenager in a Pink Floyd T-shirt receiving the COVID vaccineCredit: Hadas Parush
Ido Efrati
Ido Efrati

The first and second doses of the Pfizer-BioNTech coronavirus shot are highly effective at preventing infections and symptoms from the delta variant among teens, new research by Israel's health maintenance organization Clalit and Harvard University has found.

Among 12- to 18-year-olds who were fully vaccinated (one week or longer after the second dose) there was a 93 percent reduction in symptomatic COVID-19, compared to the unvaccinated group. There was also a 90 percent reduction in documented cases of infection.

The study, conducted by the Clalit HMO’s research institute in collaboration with Harvard University, drew on sample of 94,354 vaccinated adolescents, and an equivalent control group. 

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The control group matched the vaccinated one in terms of demographics, geographic location, clinical background and health-linked behaviors that are linked to risks of infection. 

The research, which was published in the New England Journal of Medicine, included people receiving the vaccine between June 8 and September 14, 2021, spanning the fourth wave of the epidemic.

A researcher manipulates proteins in a laboratory as part of COVID vaccine researchCredit: Stephane Mahe/Reuters

According to Prof. Ran Balicer, the head of innovation at Clalit, “with the outbreak of the fourth wave of the delta variant, the question arose whether the vaccine used in Israel provides sufficient protection against it, as it did against the alpha variant in January. Since most of the adolescents were first vaccinated during the later wave, estimating the efficacy of the vaccine could provide the answer.”

However, the study did not provide a precise estimate of the effects of the vaccine on the reduced intensity of the disease in cases of serious illness, since there is not enough information so far in this age group, due to the rarity of serious illness among adolescents.

Prof. Ben Rice from Harvard University, also the head of the Predictive Medicine Group at the Boston Children’s Hospital, says that the results of this observational study, which complement the clinical study done by Pfizer, provide well-grounded scientific proof regarding the efficacy of the vaccine in preventing infection and serious illness among youths, as well as regarding the efficacy against the delta variant, which is currently the dominant one in Israel and around the world.

The results show that the degree of protection against the delta variant is similar to that seen among young adults with the alpha variant, six months ago. These results provide important and confirmed information for parents who are deliberating whether to vaccinate their adolescent children. In Israel, around 1.2 million youths are inoculated.

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