COVID-19: Pfizer jab effective against Delta variant in teens, study finds

Adolescents who receive two doses of the Pfizer-BioNTech vaccine have a much lower risk of contracting symptomatic COVID-19, with the risk of infection dropping by 90 per cent, a study by Israel's Clalit Research Institute and Harvard University suggests.

The data make "a strong argument in favour of opting-in to get vaccinated, especially in countries where the virus is currently widespread," Ran Balicer, senior author of the study and chief innovation officer at the Clalit health care service, said in a press release. "These data provide much-needed real-world evidence to help parents make informed decisions about vaccinating their adolescent children," he added in a clip sent to journalists.

The study was released as countries around the world struggle with surging COVID-19 cases among children and adolescents, prompting questions about the safety of schools.

The research, which assessed vaccine effectiveness against the delta variant, looked at 94,354 vaccinated adolescents aged 12 to 18 and matched them against a control group of unvaccinated teens with identical personal, clinical and demographic characteristics. The risks dropped significantly for fully vaccinated adolescents seven- to 21 days after their second dose, the release said.

A smaller trial of 2,260 teens aged 12 to 15 that Pfizer performed in the US found the vaccine was 100 per cent effective against symptomatic disease.