A batch of DPT vaccines produced in Wuhan found to be substandard was an isolated case and the company has recalled all unused substandard vaccines, China's drug regulator said Tuesday.

Spot checks in 2017 found that a batch of 400,520 doses of DPT vaccines produced by Wuhan Institute of Biological Products Co., Ltd. failed to meet standards. The main cause of the defects was found to be a short-term failure in the packaging equipment, said a spokesperson with the State Drug Administration.

The spokesperson said all unused DPT vaccines found to be substandard have been recalled by the company and destroyed.

Tests on other batches of DTP vaccine produced by the company were conducted, and the test results show all meet standards, according to the spokesperson.

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

Wuhan Institute of Biological Products Co., Ltd was fined and its illegal gains were confiscated.

The local drug regulator demanded the company rectify improper practices and ensure the normal operation of its equipment. An inspection conducted in March by the national drug regulator found that the company had completed the rectification process, according to the spokesperson.