Developing countries racing for coronavirus vaccines now have another dependable option — and China’s reputation as a rising scientific superpower just got a big boost.

The World Health Organization on Friday declared a vaccine made by a Chinese company, Sinopharm, as a safe and reliable way to fight the virus.

The declaration marks a significant step toward clearing up doubts about the vaccine, after little late-phase clinical trial data was disclosed by the Chinese government and the company.

The WHO emergency use approval allows the Sinopharm vaccine to be included in Covax, a global initiative to provide free vaccines to poor countries. The possible inclusion in Covax raises hopes that more people — especially those in developing nations — will get access to shots at a crucial moment.

Rich countries are hoarding doses of vaccines. India, a major vaccine-maker, has stopped exports to address its worsening coronavirus crisis. Safety concerns led health authorities in some countries to temporarily pause the use of vaccines made by AstraZeneca and Johnson & Johnson.

“The addition of this vaccine has the potential to rapidly accelerate COVID-19 vaccine access for countries seeking to protect health workers and populations at risk,” Dr. Mariângela Simão, WHO Assistant-Director General for Access to Health Products, said in a statement.

Reliable vaccine access could improve even further next week when the WHO considers another Chinese shot, made by a company called Sinovac. But the fanfare may be short-lived.

While China has claimed it can make up to 5 billion doses by the end of this year, Chinese officials say the country is struggling to manufacture enough doses for its own population and are cautioning a pandemicweary world to keep expectations in check.

“This should be the golden time for China to practice its vaccine diplomacy. The problem is, at the same time, China itself is facing a shortage,” said Yanzhong Huang, a senior fellow for global health at the Council on Foreign Relations. “So in terms of global access to vaccines, I don’t expect the situation to significantly improve in the coming two to three months.”

China’s vaccination campaign got off to a slow start, in part because the government prioritized exports and residents did not feel rushed to get vaccinated. The country is now speeding up its national vaccination campaign and aims to inoculate 40 percent of its 1.4 billion people by the end of June.

Sinopharm and Sinovac are producing about 12 million doses a day, just a little more than the 10 million doses that China hopes to administer daily to meet the domestic target. The companies would have to produce roughly 500 million additional doses to meet the demands of other countries, according to a calculation of data provided by Bridge Consulting, a Beijing-based consultancy focused on China’s impact on global health.

The vaccine shortage in China underscores the complexity of rolling out a mass vaccination campaign for the world’s most populous nation while also trying to execute an ambitious export program. Companies involved in the vaccine supply chain, such as those making syringes, are working overtime.

“The whole world is short of this vaccine,” said a Sinovac spokesperson, Pearson Liu. “The demand is just too great.”

To mitigate the shortfall, Chinese officials said those getting vaccinated in China could delay getting their second shot by as long as eight weeks, or they could combine the same type of vaccine from different companies. They have said the shortage should ease by June.

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,” Taylor said. “Having potentially two options coming from China could really change the landscape of what’s possible over the next few months.”