The World Health Organization insisted Friday it would never endorse a vaccine that has not proven safe and effective, amid concerns over the rush to develop a jab for COVID-19.

Across the globe, governments are hoping to deploy a vaccine as soon as possible against the virus, which has infected well over 26 million people, killed hundreds of thousands, upended millions of lives and wreaked havoc on the global economy.

“WHO will not endorse a vaccine that is not effective and safe,” the organisation’s director-general Tedros Adhanom Ghebreyesus told a virtual briefing.

Tedros welcomed several candidate vaccines for COVID-19 having moved to advanced stages of testing, and voiced hope that one would soon become available “so that the world can get back to normal.”

But while the WHO has said it expects to see results from a range of Phase III final-stage trials by the end of the year, it on Friday tempered hopes that a vaccine is imminent, saying widespread vaccination is not expected to begin until the middle of 2021.

Under normal procedures, test administrators must wait for months or years to verify that vaccine candidates are safe and efficacious.

But as the pandemic continues to take a devastating toll, there has been massive pressure to roll out a vaccine quickly, sparking concerns that testing standards could be lowered.

“They will only be used when they are found to be effective and safe. That I would like to assure the world,” Tedros said, stressing that standards are ensured by WHO and national health authorities.

The WHO chief meanwhile took issue with the so-called anti-vax movement, stressing that they might be able to “build narratives to fight against vaccines, but the track record of vaccines tells its own story.”

He pointed to how vaccines over the decades helped eradicate smallpox and nearly eradicate polio, and recently making it possible to end a deadly Ebola outbreak in eastern Democratic Republic of Congo.

“Please go to the track record of vaccines and have a look for yourselves. Especially parents… and see how vaccines actually changed the world,” he said.