The Pfizer-BioNTech vaccine is 100% effective against the coronavirus in 12 to 15 year olds, the companies announced on Wednesday. Phase three trials were carried out on 2,260 adolescents in the United States. But data from the trial has not yet been peer-reviewed nor published in a scientific journal.

In the trial there were 18 cases of coronavirus in the group that got a placebo shot and none in the group that got the vaccine, resulting in 100% efficacy in preventing the infection, the companies said in a statement. The children also produced strong antibody responses and experienced no serious side effects, it added.

The companies also studied a subset of teens to measure the level of antibodies a month after the second dose and found it was comparable to trial participants aged 16 to 25.

Pfizer chief executive Albert Bourla said the companies will submit the data to the US’ Food and Drug Administration and to other drug regulators around the world in the coming weeks. “We share the urgency to expand the authorisation of our vaccine to use in younger populations and are encouraged by the clinical trial data from adolescents between the ages of 12 and 15,” Bourla added.

Pfizer hopes that vaccinations of the group could begin before the next school year, Bourla said.

BioNTech Chief Executive Ugur Sahin said people across the globe were “longing for a normal life”, especially children.

“The initial results we have seen in the adolescent studies suggest that children are particularly well protected by vaccination, which is very encouraging given the trends we have seen in recent weeks regarding the spread of the B.1.1.7 UK variant,” he added. “It is very important to enable them to get back to everyday school life and to meet friends and family while protecting them and their loved ones.”

Akiko Iwasaki, an immunologist at Yale University, told The New York Times that if the performance of the vaccines in adults was A-plus, then the results in children were “A-plus-plus.”

Children under 18 account for about 23% of the population in the US and vaccinating them will be critical to stopping the pandemic. While children are far less likely than adults to get seriously sick because of the infection, at least 268 have died in the US alone and more than 13,500 have been hospitalised, AP reported, citing data from the American Academy of Pediatrics.

The Pfizer/BioNTech vaccine was authorised by US regulators in late December for people aged 16 and older. After that, more than 65 countries have used it to vaccinate millions of adults against the infection, according to AFP.

Results are also expected soon from a study of Moderna’s vaccine in 12 to 17 year olds in the US.

Globally, the coronavirus has infected 12,81,44,389 people and killed 28,02,066, according to the Johns Hopkins University tracker. As many as 7,26,76,421 have recovered from the disease.