Australia has canceled an order for 51 million doses of a Covid-19 vaccine being developed by CSL Ltd after trials ran into difficulties.

The CSL failure shows that despite the groundbreaking progress by Pfizer Inc. and Moderna Inc. in producing an inoculation, the path to a successful vaccine remains difficult.

According to Aljazeera news, the Australian government said  it is replacing most of the CSL doses with more purchases of other planned vaccines.

The government also added that Australia has ordered an extra 20 million shots being developed by the University of Oxford and AstraZeneca Plc, and 11 million more Novavax Inc. doses.

However the Australian Minister of Health Greg Hunt said  even without CSL’s doses, more than 140 million units of vaccines will be available in Australia.