Chinese Premier Li Keqiang has ordered an immediate investigation into the DPT vaccine scandal as Beijing scrambles to contain the country’s latest public health crisis that has left parents angry and scared, South China Morning Post reported.

The incident, he said in statement issued just before midnight on Saturday, had crossed a “moral bottom line”.

He ordered an investigation into the “complete production and sale processes” of the vaccines and threatened “resolute punishment” for the companies and people involved

Meanwhile, officials in the east Chinese province of Shandong said that there had been no reports of any children sickened by the inferior vaccines.

In a report on Monday, newspaper Dazhong Daily quoted the Shandong Centre for Disease Control and Prevention as saying that while the DPT vaccines, which are used to inoculate children against diphtheria, pertussis (whooping cough) and tetanus, are ineffective they are not thought to be harmful.

It said also it had records for all 215,184 children who were given the shots.

In the latest scandal it is thought that hundreds of thousands, if not millions, of Chinese children – some as young as three months old – might have been injected with ineffective vaccines, made by the country’s largest producers, under a compulsory government health care system.

Fury and fear filled China’s social media over the weekend as parents questioned how such a scandal could have been allowed to happen.

On WeChat, the country’s most popular messaging service, the Chinese word for vaccine appeared in 321 million articles and searches, 80 times the number of times it appeared on Friday.

The latest company to become embroiled in the scandal is Changsheng Bio-technology, which is based in Changchun, capital of northeast China’s Jilin province.

The provincial food and drug administration said on its website on Friday that the company sold about 252,600 substandard DPT vaccines to the Shandong Centre for Disease Control and Prevention, the agency in charge of public health in a province of about 100 million people.

For that offence Changsheng Bio-technology was fined 3.4 million yuan, but it was also revealed that the company had been guilty of another serious violation over the manufacture of rabies vaccines.