Two Chinese vaccine makers Thursday confirmed they have shut down operations after their rabies vaccines were found to be substandard.

The State Food and Drug Administration (SFDA) announced in December that a total of 215,800 units of rabies vaccines made by Jiangsu Ealong Biotech Co. and Hebei Bioforwell Co. from July to October 2008 had quality problems.

The agency had ordered the two companies to halt production and sales.

The confirmation came after media reports saying Ealong Biotech had resumed production and seven executives had been detained. Reports said the company had mixed an additive with the vaccine to reduce costs, leaving as many as 1 million people affected nationwide.

Some local newspapers even reported that deaths or illness were likely caused by the faulty vaccines.

Yan Jiangying, the SFDA spokesman, said the SFDA was yet to release investigation results as the probe was still underway.

But Yan said people needed several injections to build up immunity as the 180,000 units of vaccines made by Ealong Biotech were not as effective as required by the drug watchdog.

Liu Wu, general manager of Ealong Biotech, said the faulty vaccines may not provide protection against rabies as they were not up to national standards.

But Liu said "We have not received any reports on adverse reactions in people receiving rabies vaccine shots."

Liu also denied there were 1 million people affected, saying each person should receive five injections, or one unit, rather than receive one injection of each unit.

The company had not produced or sold even one dose of rabies vaccine since Nov. 30, Liu told Xinhua.

It also halted production of the A/H1N1 flu vaccine in February when the quality permit expired, he said.

Liu also denied that seven company executives had been arrested and that they had put an additive in the vaccines.

Ealong Biotech is the nation's fourth-largest rabies vaccine maker with a market share of 11 percent. It took orders from the Chinese government for 6.3 million doses of A/H1N1 flu vaccines in 2009, ranking third nationwide.

Wang Kejing, deputy director of the food and drug administration in Sanhe city, where Hebei Bioforwell Co. is located, said the company had not sold even one dose of vaccine since April last year.

Hebei Bioforwell Co., which only produced rabies vaccines, had been shut down for rectification. It said earlier that all the faulty rabies vaccines had been used, but they had received no reports of adverse reactions.

In the northern Shanxi province, almost 100 children had died or fell ill after taking shots of vaccines for encephalitis, hepatitis B and rabies, the Beijing-based China Economic Times reported on March 17.

The Ministry of Health has launched an investigation into the case after media exposure.