Small bottles labeled with a "Vaccine COVID-19" sticker and a medical syringe are seen in this illustration taken taken April 10, 2020. (PHOTO PROVIDED TO CHINA DAILY)

China's CanSino Biologics Inc said on Wednesday that no serious blood clot cases had been reported so far in people who were injected with its COVID-19 vaccine Ad5-nCoV.

The announcement follows US federal health agencies’ recommendation on Tuesday that use of Johnson & Johnson’s COVID-19 vaccine, which uses a similar technology to CanSinoBIO’s product, should be paused for at least a few days, after six women younger than 50 developed rare blood clots after receiving the shot.

Vaccines from Johnson & Johnson and CanSinoBIO contain another virus called adenoviruses, which have been modified to essentially render them harmless

“No blood clot related serious adverse events have been reported in around one million vaccinations of Ad5-nCoV,” CanSinoBIO said in a filing.

CanSinoBIO’s shares fell as much as 13.7 percent and 18.4 percent in Shanghai and Hong Kong, respectively, in morning trading.

READ MORE: China approves clinical trials for CanSino's inhaled vaccine

Vaccines from Johnson & Johnson and CanSinoBIO contain another virus called adenoviruses, which have been modified to essentially render them harmless.

The adenoviruses are employed as a vector to ferry instructions for human cells to make parts of the new coronavirus, triggering the immune system to produce antibodies against it.

ALSO READ: CanSino's adenovirus vector shot to 'provide 2-year protection'

CanSinoBIO’s COVID-19 vaccine, which has been approved in China and secured deal in Mexico, uses a different adenovirus than that for Johnson & Johnson’s.