One dose of the Pfizer-BioNTech vaccine offers two-thirds protection against COVID-19, data seen by the U.K. government suggests.

Early findings from the U.K.’s vaccination program, due to be released within days, show that the first dose reduced the symptomatic infection risk among patients by 65% in younger adults and 64% in over-80s, a person familiar with the matter said.

The data, first reported by The Sun newspaper, showed that two doses of the Pfizer vaccine saw protection rise to between 79% and 84%, depending on age. The AstraZeneca vaccine offers similar protection, the newspaper said.

While efficacy results are lower than those found in Pfizer’s clinical trials, Boris Johnson’s government is likely to hail the U.K.’s first real-world data as a significant boost to its efforts to immunize the population. A successful mass vaccine rollout is key to the government’s hopes of reopening the economy after months of lockdown.

More than 12.6 million people in the U.K. have so far received their first doses of either the Pfizer shot or the Oxford-AstraZeneca vaccine, according to latest data published Tuesday.