State Council investigators have discovered two batches of 499,800 defective DPT vaccines produced by Changchun Changsheng Life Sciences Limited.

The investigation team will step up efforts to investigate related vaccines, pledging to hold officials neglecting regulatory responsibilities accountable.

The vaccines were sold to the provinces of Shandong and Anhui, and 76.2 percent of children who had used the first batch of unqualified DPT vaccines, labeled "201605014-01", were revaccinated.

Meanwhile, health and drug authorities have made plans for those subjected to the second batch of vaccines, labeled "201605014-02", to renew their vaccinations.

In October 2017, the DPT vaccine produced by Changchun Changsheng Life Sciences Limited was found to be defective. The company's DPT vaccine production has since been suspended.

DPT refers to a combination of vaccines against three infectious diseases: diphtheria, pertussis, and tetanus.