The World Health Organization chief hailed as "encouraging" Pfizer and BioNTech's announcement Monday that their vaccine has in trials proved 90-percent 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 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.