A medical worker gives a polio vaccine to a child in Hami prefecture in Northwest China's Xinjiang Uygur autonomous region in an undated photo. [Cai Zengle / for China Daily]

JINAN, March 21 -- The food and drug administration of East China's Shandong Province on Monday made public a list of problematic vaccines illegally sold in 18 provinces since 2011.

The 12 vaccines, 2 immune globulin and one therapeutic product were allegedly sold by a mother and daughter, who were arrested in Shandong.

China's drug regulator and police are trying to trace them, which are worth more than 570 million yuan (88 million U.S. dollars), and have given pharmaceutical companies and distributors involved a deadline of March 25 to come up with information about the whereabouts of the vaccines.

The two women were engaged in the purchase and sale of vaccines for a profit. Though produced by qualified manufacturers, the vaccines were not transported in approved conditions and so quality cannot be guaranteed. Such vaccines have potential side-effects and may even cause disability and death.

The case has been transferred to the procurators.