Local governments have been urged by food and drug administration to investigate approximately 570 million yuan ($88 million) worth of improperly refrigerated vaccines sold since 2010, which could put patients' lives at risk.

The suspects, a mother surnamed Pang and her daughter, surnamed Sun, who graduated from medical school, have been bulk-selling 25 kinds of vaccines for adult and children through unlawful businesses since 2010. The vaccines were allegedly sold to 18 provincial regions, Zhai Jinliang, an officer of public security bureau of Ji'nan, capital of East China's Shandong Province, told news site thepaper.cn.

According to Ji'nan police, the vaccines were purchased by 247 people in over 10 provincial regions including Chongqing as well as Shaanxi and Jilin provinces, spreading across 18 regions including Henan, Anhui and Guangdong provinces. The vaccines include flu, hepatitis B and rabies.

The China Food and Drug Administration has urged local departments to investigate and confiscate suspect vaccines, while working with the health authorities to assess the damage done.

Pang's bank account saw some 310 million yuan of income in the past five years. Local police have yet to release an exact number of vaccines sold, but a rough count based on an average price of 150 yuan per vaccine sold would put the number at over 2 million, thepaper.cn noted.

The suspects have been charged with running an illegal business and are waiting for a trial, thepaper.cn said, adding that some 20 cities have been urged to cooperate with the investigation and verify the vaccine's users.

Another six suspects have been arrested in areas including Inner Mongolia, Hebei and Shandong, while another 10 have been detained.

"This is homicide," Wang Yuedan, deputy director of the immunology department at Peking University Health Science Center was quoted as saying. Wang explained that vaccines transported without being properly refrigerated between 2 and 8 C could lose effectiveness and recipients could die from infection complications.

According to local police officer Chen Bo, the temperature of the vaccine warehouse was close to 14 C when the mother and daughter were arrested and the vaccines were stored without refrigeration.

Pang, 47, once worked as a pharmacist at a hospital in Heze, Shandong and has also run a clinic selling vaccines. She is also reportedly well known for her close connections with pharmaceutical companies. In 2009, she was put on probation for illegally selling vaccines and she remains on probation, according to thepaper.cn.

While companies can only sell vaccines after getting approval from food and drug authorities, organizations authorized for injection must ask for a certificate of quality when purchasing vaccines and a two-year-valid archive must be set up for the vaccines, jkb.com.cn, a news site affiliated with the National Health and Family Planning Commission, reported Friday.

However, as the vaccines are supervised by the food and drug administration, which has a low administrative status, it is hard for vaccine watchdogs to effectively perform their duties when the vaccines are used in health departments, news site caixin.com reported, citing unnamed former food and drug officials.