The city of Harbin, Heilongjiang province has set up an investigative team to trace the problems with vaccines after a recent scandal, involving a mother and daughter from Shandong province, triggered widespread concern about drugs in China.

The incident was exposed after police arrested the two female who allegedly sold vaccines worth 570 million yuan ($88 million) illegally since 2010, in what is believed to be the largest case of its kind in China in the amount of money involved, according to media reports.

Shandong food and drug officials published a notice on hundreds of tips that linked 300 suspects to illegal vaccine deals in 24 provinces, municipalities and autonomous regions, on March 19, showing 11 suspects who had cell phone numbers from Heilongjiang and six in Harbin.

The city’s food and drug officials are examining the purchasing and sales channels of these problematic vaccines and are working with public security and health authorities to conduct a thorough investigation. They said they will report the results to their superiors and make the news public. The vaccines were produced by qualified manufacturers but were not transported under approved conditions so their quality could not be guaranteed. Experts say that these vaccines could have side-effects or could even cause disabilities or death.