Among the most widely used vaccines that don't meet that criteria are Russia's Sputnik V vaccine and China's CanSino vaccine. Sputnik V is authorized for use in more than 70 countries while CanSino is allowed in at least nine countries. WHO still is awaiting more data about both vaccines before making a decision.
Vaccines recognized by the FDA and WHO undergo rigorous testing and review to determine they're safe and effective. And among the vaccines used internationally, experts say some likely won’t be recognized by the agencies.