A pharmaceutical company in East China's Jiangsu province admitted on Thursday that their substandard rabies vaccines might expose unwitting patients to the hazards of bogus immunizations, Xinhua News Agency reported.

Media reports also confirmed that at least 8,600 shots of the shabby vaccine have already been used in eastern Jiangxi province alone, and more than 20,000 doses have been distributed in neighboring Guangzhou, resulting in at least five cases of adverse reactions.

Liu Wu, president of Jiangsu Ealong Biotech Co. also known as Jiangsu Yanshen, told Xinhua that four batches of their rabies vaccines produced in 2008 fell short of the national titer criteria and were too diluted to produce the desired immunity.

The four shabby batches are "Yanshen 20080732", "Yanshen 20080834", "Yanshen 20080837" and "Yanshen 200810F01".

So far, 8,600 doses of the faulty batches have been used in east China's Jiangxi province, raising red flags throughout Ganzhou, Ji'an, Dexing, Yingtan cities and Xinguo County, according to the China News Agency.

Since last September, when the State Food and Drug Administration issued a warning bulletin on Yanshen's rabies vaccine, the Jiangxi provincial health department has carried out an emergency re-vaccination, but they admitted the uphill task of retracing all former recipients seems almost impossible.

In neighboring Guangdong province, an additional 23,340 shots have been distributed, mainly in Foshan, Maoming and Yangjiang cities, with at least five reports of adverse reactions, although they were mild and have already recovered, local Yangcheng Evening News reported Thursday.