(Bloomberg) -- China National Biotec Group Co. said none of the recipients of its two coronavirus shots has reported an obvious adverse reaction or infection, as the Chinese vaccine front-runner presses ahead with testing after AstraZeneca Plc suspended its trial.

Hundreds of thousands of people have received the Covid-19 shots so far, the vaccine developer, a subsidiary of state-owned drugmaker Sinopharm Group Co., said on its official WeChat account. The vaccine is being administered under an emergency-use program that allows experimental shots to be used for frontline workers before they complete final testing.

CNBG’s two shots are among a handful of the world’s fastest-moving coronavirus vaccine candidates now in the final stage of testing. AstraZeneca set off alarm bells Tuesday as an illness from a single person cause it to suspend its phase III trial.

The incident was a reality check for high expectations that vaccines would soon help control the coronavirus pandemic even as drugmakers move at unprecedented speed to develop Covid-19 shots.

Putting trials on hold when participants fall sick is routine in clinical trials, and could be evidence of a significant side effect or entirely unrelated to the vaccine. But the development from one of the world’s most promising and high-profile candidates highlights the need for discipline in the rush to get vaccines approved for mass innocolation.

Governments around the world are scrambling to secure supplies of shots that have yet to be proved safe and effective, as they bet on vaccines as the best solution to eradicate rampant infections and salvage crippling economies.

A CNBG spokeswoman said in an interview Thursday the suspension of the AstraZeneca trial has no impact on the final stage of testing for the Chinese company’s two shots, which she said has been progressing smoothly. The company will follow relevant guidelines should an adverse event occur during the phase III trials, she added.

The company’s shots are made using inactivated coronavirus to stimulate an immune response without causing Covid-19. That’s different from the AstraZeneca candidate, which uses a chimpanzee adenovirus to deliver a component of the coronavirus

CNBG’s coronavirus vaccines, which are being tested in countries in the Middle East and South America, may be available to the public as soon as the end of the year, according to the company’s WeChat statement. The company said it has invested about 2 billion yuan ($292 million) in the construction of two high-grade production facilities and is studying plans to further expand capacity to produce as many as 1 billion doses a year.

Under China’s emergency-use program, pregnant and breastfeeding women are currently barred from taking the vaccine. The exclusion is based on a lack of sufficient data for this population group, according to Zhou Song, CNBG’s general counsel.

©2020 Bloomberg L.P.