W.H.O. approves China’s Sinopharm vaccine for emergency use.

Andrea Taylor, who analyzes global data on vaccines at the Duke Global Health Institute, called the potential addition of two Chinese vaccines into the Covax program a “game changer.”

“The situation right now is just so desperate for low- and lower-middle-income countries that any doses we can get out are worth mobilizing,” Ms. Taylor said. “Having potentially two options coming from China could really change the landscape of what’s possible over the next few months.”

For China, the approval represents a high point in its vaccine diplomacy efforts and a chance to fill the gap left by Western nations and pharmaceutical companies in low- and middle-income countries. Sinopharm is the first Chinese shot to be classified as safe and effective by the W.H.O., and its approval could ease concerns about the lack of transparency from Chinese vaccine companies.

Regulators from China and other countries have approved the Sinopharm vaccine in recent months, though the company has not released Phase 3 clinical trial data for scientists to independently assess.

The W.H.O. was given access to this data before the announcement, but there is limited data on how well the vaccine will work against the many coronavirus variants cropping up around the world.