China's drug regulator and police are busy tracking down more than 570 million yuan's (88 million U.S. dollars) worth of vaccines sold illegally in 18 provinces since 2011.
A mother and daughter suspected of selling the vaccines were arrested in Shandong Province last week.
The China Food and Drug Administration (CFDA) on Sunday gave pharmaceutical companies and distributors involved a deadline of March 25 to come forward with information about the whereabouts of vaccines.
Although produced by licensed manufacturers, the quality of the vaccines might be questionable as they were not transported and stored properly.
The CFDA urged any pharmaceutical companies and dealers who had done business with the suspects to inform local drug regulators or police about their transactions, for instance what kind of vaccines they sold to or bought from the suspects and where the vaccines went later.
Police obtained nearly 200 leads from the suspects concerning vaccine suppliers and buyers. These companies and individuals have been told they must come forward by March 23 or face "serious punishment."
The suspects allegedly purchased 25 types of vaccines from more than 100 pharmaceutical salesmen, both licensed and unlicensed, and sold them to illegal agents or even local disease control and prevention centers at high prices, according to Jinan police in Shandong.
