I should qualify that first - it was a 'false positive' supposedly.

A vaccine developed at the University of Queensland, Australia (aside: this uni is notoriously influenced by the CCP) used two HIV protein fragments in the construction of their vaccine. This resulted in all the participants developing antibodies to HIV, hence the positive test.

The UQ scientists responsible say that the participants are not at risk of contracting HIV - though trials of the vaccine have been abandoned.

Interestingly, Australian vaccine scientist Nikolai Petrovsky, having reviewed the initial data, tried to warn the government months before it went ahead and invested big-bucks in the vaccine but "No one wanted to listen." (paywall)

“There’s a chunk of HIV protein that they’ve used to attach to the vaccine that was always going to be a problem because it induces most of the immune response against the tag. That was clear in their hamster and mouse data.”

“We were concerned by the level of antibodies that they were generating against the clamp which were against HIV. They didn’t call it that, they just said we’re inducing all of these antibodies against the clamp. But given that the clamp is from HIV obviously that means you’re generating antibodies against HIV."