Thirty-three people are being held accountable after 145 babies in Jinhu county, Jiangsu province, were given expired polio vaccine, local authorities announced on Sunday.

The Huaian city government, which has jurisdiction over the county, said on its website that Gu Kun, a vice-mayor of the city, and Sun Banggui, director of its health commission, have been given administrative warnings.

Zhang Zhiyong, the Party secretary of the county, and Xu Yaping, who heads the government, have been given serious Party warnings.

Wang Hong, head of the Licheng Health Center, where the vaccinations were given, has been detained on suspicion of duty-related crimes.

Six people directly involved in the incident, including Liu Zhibing, deputy head of the center, have been dismissed from their posts and the Party. Liu has been transferred to judicial authorities for prosecution.

The babies received expired polio vaccine at the health center in the county's Licheng township from Dec 11 to Jan 7. The incident came to light in early January, after a father who is a medical worker took his son to the center to get the vaccine. When he checked the batch number printed in the boy's vaccination record book he found it had expired.

The provincial government sent a special team to investigate the incident. Examinations of the babies conducted by medical experts found that none had acquired abnormal health conditions related to the expired vaccine.

The operations of the health center in Licheng have been corrected, and it has reopened for vaccinations, the city government website said.

The provincial government ordered Jinhu county to conduct in-depth reviews and apologize to the provincial and city governments. The city government and the provincial health commission have also been told to conduct reviews and apologize to the provincial government.

The province is formulating a plan to improve the vaccine management system and clarify the responsibilities of local governments, regulatory authorities and medical institutions.

The safety of vaccines became a hot topic last year when Changchun Changsheng, one of the country's major vaccine producers, was found to have fabricated production records and to have used expired materials from 2014 in the production of rabies vaccine. It also produced a substandard DTaP vaccine, which protects against diphtheria, tetanus and whooping cough.