GENEVA, Switzerland (AFP) — The World Health Organization chief hailed as “encouraging” Pfizer and BioNTech’s announcement Monday that their vaccine has in trials proved 90-per cent effective in preventing COVID-19 infections.

The two pharmaceutical companies said the vaccine they have jointly developed had during Phase 3 trials provided protection to nearly all patients seven days after the second of two vaccine doses.

“We welcome the encouraging vaccine news from @pfizer & @BioNTech_Group & salute all scientists & partners around the world who are developing new safe, efficacious tools to beat #COVID19,” WHO director Tedros Adhanom Ghebreyesus said in a tweet.

“The world is experiencing unprecedented scientific innovation & collaboration to end the pandemic,” he said.

As of mid-October, the WHO has identified 42 “candidate vaccines” at the stage of clinical trials, up from 11 in mid-June.

Ten of them were at the most advanced phase 3 stage, in which a vaccine’s effectiveness is tested on a large scale, generally tens of thousands of people across several continents.

WHO chief scientist Soumya Swaminathan said in a tweet Monday that the news from Pfizer and BioNTech should “encourage all developers of #COVID19 vaccines to continue with clinical trials”.

“The world needs several safe, effective & affordable vaccines to end this pandemic,” she said.