WHO Director-General Tedros Adhanom Ghebreyesus called for countries around the world to join forces to tackle the coronavirus on Friday, saying that "vaccine nationalism" would only slow the response to the pandemic.
The WHO and GAVI vaccine alliance are leading a global vaccine allocation plan known as COVAX aimed at helping buy and distribute vaccination shots fairly.
But some countries that have secured their own supplies through bilateral deals, including the United States, have said they will not join COVAX.
"Vaccine nationalism will prolong the pandemic," Tedros told reporters at a WHO briefing in Geneva, without mentioning any specific countries.
Covid vaccine must be proven safe before mass rollout
WHO chief scientist said that no vaccine for the new coronavirus should be approved for a worldwide rollout until it had undergone sufficient scrutiny and proved its safety and efficacy.
"No vaccine is going to be mass-deployed until regulators are confident, governments are confident, and the WHO is confident it has met the minimum standard of safety" WHO chief scientist Soumya Swaminathan said at a news briefing in Geneva.