The factory used disinfectants and obsolete disinfectants when producing Brucella vaccines for animals.
The contaminated waste gases then formed aerosols, which contained bacteria and spread into the air.
The possibility of human-to-human transmission is said to be extremely rare.
It is believed that most people get infected by eating contaminated food or inhaling the bacteria.
Brucellosis is an infectious bacterial disease that spreads from animals to humans.
It commonly occurs in dogs, sheep, cattle, goats, and pigs.
The news comes as China remains caught in the midst of the COVID-19 pandemic as the invisible killer disease continues to spread in the country it originated from in December last year.
Mainland China reported nine new cases of COVID-19 as of September 16, up from 12 the day before, the country’s national health authority said Thursday.
The National Health Commission said in a statement that all of the new cases were imported infections involving travelers from overseas. The number of new asymptomatic patients also fell to 14 from 16 a day earlier, although China does not count these patients as confirmed cases.
The total confirmed cases of COVID-19 in mainland China now stands at 85,223, while the death toll remained unchanged at 4,634.