Australia’s hopes of a locally developed COVID-19 vaccine have been dashed with news today the University of Queensland/CSL vaccine would not proceed to further clinical trials.

According to a statement to the Australian Stock Exchange (ASX) earlier today, CSL said participants in the phase 1 trial received “false positive” results to HIV tests. They were not infected with HIV, nor did the vaccine contain the entire HIV virus.

Rather, the vaccine’s signature “molecular clamp” technology was formulated with parts of an HIV protein. When injected, these prompted the production of antibodies that were picked up in a range of HIV tests. In other words, if the vaccine had been widely rolled out, this could lead many people to think they had HIV when they didn’t.

How could a COVID vaccine lead to a positive HIV test?

The UQ/CSL vaccine uses “molecular clamp” technology to stop the coronavirus spike protein from “wobbling about”. This more stable presentation is more likely to lead to a protective immune response.

The molecular clamp in UQ’s vaccine contains part of an HIV protein, a string of 80 amino acids. By itself, this is harmless and cannot cause an HIV infection or AIDS.

But there was always a theoretical possibility that once injected as part of the vaccine formulation, people’s immune systems would recognise it as “foreign” and raise antibodies against it. Until now, the research team thought the chance of that happening was low. And in its ASX statement CSL said people in the 216-person trial were fully informed of this possibility.

However, from what we’ve heard today, it’s clear that people’s immune systems did recognise the HIV protein fragment in the molecular clamp.

Had we rolled out this vaccine on a wider scale, we would have seen many more “false positive” HIV tests. This would have meant unnecessary anxiety while people sought further clarification about their HIV status.

It would also have undermined the public’s confidence in the COVID vaccination program. You have to have the public on board. So by acting early to clearly communicate concerns, the researchers have acted appropriately. And this should reinforce the public’s confidence in Australia’s COVID vaccination program, due to start from March 2021.