An official with the China Food and Drug Administration said Sunday they discovered that the company had fabricated production records and product inspection records, and arbitrarily changed process parameters and equipment during its production of freeze-dried human rabies vaccines.
"News about the vaccine scandal involving Changchun Changsheng is flooding the Internet with public anger and panic".
Authorities in Hebei announced on Monday that almost 150,000 people in the northern province received a sub-standard diphtheria, tetanus and pertussis vaccine made by another firm, Wuhan Institute of Biological Products.
Chinese president Xi Jinping has ordered a "thorough investigation" into widespread concerns that hundreds of thousands of infants might have been administered fake vaccines produced by one of the country's largest pharmaceutical firms.
This is not the first time substandard vaccines have been produced in China.
Changsheng apologised in a regulatory filing on Monday and said the suspension of its vaccine would hit its finances.
It is unclear whether other areas were affected by the rest of Changsheng's supply of the substandard DTap vaccine.
Despite being overseas on Monday on a visit to Africa, President Xi was briefed on the vaccine crisis and said ensuring the safety of drugs was the responsibility of the government and the Communist Party.
Changsheng has been found to have falsified production documents related to a rabies vaccine that is given routinely to Chinese babies as young as three months, underscoring the challenge the world's second-biggest drug market faces cleaning up its image as it aims to promote its vaccines globally.
He called for authorities to "scrape the poison off the bone" in their efforts to rectify the vaccine problems.
Premier Li Keqiang, member of the Standing Committee of the Political Bureau of the CPC Central Committee, instructed the State Council to immediately dispatch teams to thoroughly investigate the entire product chain - including production and sale - of all vaccines.
"Those involved will be resolutely punished with zero tolerance".
"(We) must resolutely strike with heavy blows all law-breaking criminal behaviour, severely punish the criminals according to the law, and hold accountable those who were negligent in supervision", Li said in a website statement late Sunday.
The company is listed on the Shenzhen Stock Exchange.
However, the inferior vaccine was found in October 2017 by authorities, but the incident hadn't been made public.
'We would like to express our deepest apologies to the vaccination population and investors, ' the statement added. It also fined the company 3.44 million yuan (about $507,809).
But some social media users this week have pointed sardonically to Sun Xianze, the official in charge of food safety during the 2008 milk scandal.
In an editorial Monday, the state-run China Daily said "the investigation that has been launched must get to the bottom of the case so as to scratch the bone to get rid of the poison".
Censors and regulators struggled to stay abreast of the public's response to the latest scandal, deleting posts on WeChat over the weekend which alleged corruption in the industry.
"Not just the culprits directly responsible for the problematic vaccines, but also those responsible for enabling the sector's misdeeds need to be caught", it added.