An HIV vaccine trial called this decade’s “last roll of the dice” has halted after researchers declared the experimental shot wasn’t working.

The trial, known as PrEPVacc, was testing two vaccine regimens on approximately 1,500 people between ages 18-40 in Uganda, Tanzania, and South Africa.

Although researchers did not declare safety issues, they dubbed the trial a failure due to ineffectiveness in preventing HIV.

“The failure of the experimental vaccines is a massive blow to the medical community, which has hit countless dead ends since the first HIV vaccine trial began 36 years ago,” CNN wrote.

We spent 4 decades trying to develop a HIV vaccine and couldn’t do it. But somehow the world was convinced we could develop a ‘safe and effective’ Covid vaccine in less than a year. Insanity,” IT Guy noted.

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“The trial of a pre-exposure prophylaxis pill running alongside the vaccines tests will continue,” The Guardian noted.

More from The Guardian:

Dr Eugene Ruzagira, trial director from the Uganda Virus Research Institute (UVRI) and assistant professor of epidemiology at the London School of Hygiene & Tropical Medicine, said: “Vaccinations to PrEPVacc trial participants have been stopped because an analysis of the data collected so far by our independent data-monitoring committee has led them to conclude that there is little or no chance of demonstrating that the vaccines we are testing are reducing the risk of acquiring HIV.”

The PrEPVacc trials, led by African researchers with support from European scientists, tested two different combinations of HIV vaccines to see if either could prevent infection in populations particularly at risk of infection. The trials were funded with a €15m (£12.8m) grant from the EU’s European & Developing Countries Clinical Trials Partnership.

Prof Jonathan Weber, from Imperial College London, one of the trial’s sponsors, said: “We do clinical trials because we don’t know the answer to questions. It was important to find out whether the combination vaccine regimens in PrEPVacc, developed over 20 years, should be ruled out or further developed for preventing HIV.

“While we await the final results and analysis of individual products, I believe that our interim result puts this generation of putative HIV vaccines to bed,” he said.

STAT News added:

Although disappointing, the news may not surprise many HIV vaccine researchers. PrEPVacc was seen as a pioneering study, both as one of the first large, African-led HIV vaccine trials and one of the first trials to incorporate PrEP, the daily antiviral pills that can dramatically reduce the risk of HIV infection.

But the trial used older vaccine designs some scientists doubted would provide adequate protection.

With the failure, there are now “no HIV vaccines being trialled for efficacy anywhere in the world,” PrEPVacc investigator Pontiano Kaleebu said in a statement.

Efforts are limited to small, early-stage trials designed to test new technologies that might stand a chance against the wiliest virus humanity has ever encountered. Kaleebu said there now had to be “greater urgency” to push these technologies forward.

“We have come so far in our HIV prevention journey, but we must look to a new generation of vaccine approaches and technology to take us forward again,” he said. “We must also look to a new generation of leaders. We set up PrEPVacc to grow our capacity in Africa to do future trials ourselves and to develop those who will lead them here in Africa.”

The new strategies include sending HIV “wanted” posters to a specific set of immune cells by encoding them in another, more benign chronic virus. More popular is an approach called germline targeting, where researchers give a series of different jabs designed to nudge the immune system toward making the perfect, HIV-snaring antibodies.

Moderna, the National Institutes of Health, and IAVI (formerly known as the International AIDS Vaccine Initiative) have all invested in the latter.

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