Australia has hit a major hurdle in its attempt to secure millions of doses of a promising candidate vaccine against the coronavirus disease (Covid-19) after trial participants tested false positive for HIV. The Australian government had agreed to purchase 51 million doses of the Covid-19 vaccine developed by biotechnology firm CSL Ltd and the University of Queensland (UQ).
The government had reached an agreement with CSL Ltd to manufacture two potential coronavirus vaccines: one developed by the University of Oxford and AstraZeneca, and the other by CSL’s own laboratories in collaboration with the UQ. However, CSL will not advance the candidate vaccine to Phase 2/3 clinical trials, as the Phase 1 data showed the generation of antibodies that interfered with “certain HIV tests.”
What are the concerns of the people involved in the trial?
CSL and Columbia University said in a joint statement that there is no possibility of the vaccine causing infection, adding that routine tests confirmed that the HIV virus is not present. CSL stated that the generation of antibodies was directed towards fragments of a protein (gp41), which is a component used to stabilize the vaccine.
“The trial participants were fully informed of the possibility of a partial immune response to this component, but it was unexpected that the induced levels would interfere with certain HIV tests,” he added.
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What are the implications for vaccine launch?
Australia had ordered 51 million doses of the UQ / CSL vaccine and the company was working on phase 2/3 of the clinical trial and large-scale manufacturing of the vaccine. CSL and the Australian government have agreed not to proceed to Phase 2/3 trials. The government is increasing the purchase of the Oxford-AstraZeneca vaccine from 33.8 million doses to 53.8 million doses. Doses of the Novavax vaccine have also increased from 40 million to 51 million.
How did the researchers react?
Professor Paul Young, UQ’s co-director of the vaccine, said that while there were no guarantees, the core technology approach used in developing the vaccine has passed primary clinical testing. Young added that it was possible to redesign the vaccine, but the team couldn’t afford the necessary time.
“Doing so would delay development for another 12 months or more, and while it is a difficult decision to make, the urgent need for a vaccine should be everyone’s priority,” he said.
CSL Chief Scientific Officer Dr. Andrew Nash said the result highlights the risk of failure associated with early vaccine development. It also reported that CSL agreed at the request of the Australian government to manufacture an additional 20 million doses of the Oxford-AstraZeneca candidate vaccine.