China’s drug regulator on Monday ordered local branches to track down 570 million yuan (HK$683 million) in vaccines sold on the black market in the country’s biggest public health scandal since 2008. The China Food and Drug Administration ordered the branches to work with local health and public security authorities to find out where the vaccines ended up and release details publicly. About 300 dealers in 24 provinces allegedly bought the vaccines from or sold them to a mother and daughter in Jinan, Shandong. Vaccine manufacturers and trading companies have to report their dealings with the suspects by Friday and the results will be released publicly. READ MORE: Vaccine scandal: hundreds involved across 24 provinces in China Among the dozen types of vaccines traded were those used against chicken pox, rabies, meningitis and hepatitis A. They were made by licensed manufacturers, but were expired or improperly refrigerated. The scandal is the biggest public health scare for parents since 2008 when 22 dairy firms were found to have added melamine to raw milk, killing six children and sickening 300,000 others. Children’s vaccines are classed as either category 1 – free and compulsory – or category 2 – voluntary and paid for by individuals. Some parents opt for category 2 shots because they are seen as offering wider coverage and having lower risk. All of the vaccines involved in the scandal are category 2. READ MORE: Industry ‘hijacked dairy standards’ One parent wrote in an online post that the case was “another national shame”.“I always opted for the paid vaccines rather than the free shots and now this has happened. There is no talk of the future if babies’ health is ignored,” the parent said. The father of a two-month-old daughter in Beijing said he was “shocked speechless” by the delay in making the information public. “The mother and daughter were detained in April last year. How come the details were released this weekend and drug regulators were ordered to check only now?” he said. .