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Prime Minister Scott Morrison takes a tour of the Scientia Clinical Research Ltd laboratory at Randwick in Sydney, Australia.
ANALYSIS: Australia’s hopes of producing a locally developed Covid-19 vaccine were dashed today by news that the University of Queensland / CSL vaccine will not proceed to further clinical trials.
However, unlike the news about the Pfizer / BioNTech Covid vaccine earlier this week, there were no safety concerns with the UQ / CSL vaccine.
According to a statement from the Australian Stock Exchange (ASX) earlier today, CSL said participants in the phase 1 trial received “false positive” HIV test results. They were not infected with HIV, nor did the vaccine contain all of the HIV virus.
In contrast, the vaccine’s signature “molecular clamp” technology was formulated with parts of an HIV protein. When injected, they triggered the production of antibodies that were detected in a variety of HIV tests. In other words, if the vaccine had been widely implemented, this could lead many people to think they have HIV when they are not.
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The news prompted the Australian government to announce that it had canceled its agreement to supply the UQ / CSL vaccine, which always depended on the successful completion of clinical trials.
Instead, the government will supply more doses of other vaccines, including an additional 20 million doses of the Oxford University / AstraZeneca vaccine, which will be manufactured by CSL.
The Oxford / AstraZeneca vaccine is the first Covid vaccine with published peer-reviewed results from phase 3 clinical trials, an important milestone.
In addition to the Oxford / AstraZeneca vaccine, there are agreements in place to supply Australians with Pfizer / BioNTech and Novavax vaccines, if they are safe and effective. That’s just like the vaccines available under the COVAX deal backed by the World Health Organization.
How could a Covid vaccine lead to a positive HIV test?
The UQ / CSL vaccine uses “molecular clamp” technology to present the coronavirus spike protein in the best orientation to elicit an immune response. In other words, the molecular clamp prevents the spike protein from “moving.” This more stable presentation is more likely to lead to a protective immune response.
The molecular clamp of the UQ vaccine contains part of an HIV protein, a chain of 80 amino acids. On its own, this is harmless and cannot cause HIV infection or AIDS.
But there was always the theoretical possibility that once injected as part of the vaccine formulation, people’s immune systems would recognize it as “foreign” and generate antibodies against it. Until now, the research team thought the chance of that happening was low. And in its ASX statement, CSL said that the people in the 216-person trial were fully informed of this possibility.
However, from what we have heard today, it is clear that the human immune system recognized the HIV protein fragment in the molecular clamp.
If we had launched this vaccine on a broader scale, we would have seen many more “false positive” HIV tests. This would have meant unnecessary anxiety while people sought further clarification on their HIV status.
It would also have undermined the public’s trust in the Covid vaccination program. You have to have the public on board. So by acting early to clearly communicate concerns, investigators have acted appropriately. And this should bolster public confidence in Australia’s Covid vaccination program, which will begin in March 2021.
Is this the end of UQ’s ‘molecular clamp’ technology?
This particular molecular clamp is exclusive to UQ. So while this particular type will not be used for future vaccines, researchers are likely to investigate and modify it to reduce the possibility of further HIV cross-reactivity.
I certainly don’t think it’s the end of this technology.
Where does this lead us?
We have always known that not all Covid-19 vaccines in early clinical trials would be successful. Security problems or lack of protection will stop some. But in this case, we had something different: a complication that would lead people to believe they had HIV when they didn’t, undermining people’s trust in the Covid vaccine program.
That is why it remains important to pursue a broad portfolio of vaccine approaches and technologies. We don’t want to put all of our eggs in one basket.
It is also important to remember that while the UQ / CSL vaccine will not move into late stage clinical trials, phase 1 trials will continue and the results will be submitted for peer review in due course. That means that researchers can analyze the results in more detail. 
Adam Taylor is an early career research leader in the Therapeutics, Inflammation and Emerging Viruses Group at Menzies Health Institute of Queensland, Griffith University.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
