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Comment by anovikov | Hacker News Reader

It is so excruciatingly difficult to trial a HIV vaccine that we can easily expect it to take decades.

According to the article, the Phase 1 clinical trail will take under 2 years.

"Moderna is seeking 56 individuals, aged 18 to 50 and who are HIV-negative, for the trial, which is estimated to begin on August 19 and conclude in spring 2023"

I would imagine that larger trials would be conducted in places with rampant HIV spread, right? Which shouldn't take an inordinate amount of time.

Phase 1 is not the difficulty here....

With the COVID vaccines, the locations of the clinical trials were chosen for how rapidly the virus was spreading. Some trials even added new geographic areas with high transmission rates while they were still ongoing. Why wouldn't any large scale HIV trial not choose one of the many countries with a high transmission rate?

That's for phase III trials, which I am sure will be conducted in countries like South Africa. This is not there yet, and phase I safety trials are easiest to conduct in the vicinity of the researchers and good hospital infrastructure.

It is maybe that Moderna makes a partnership with larger drug companies for phase ii iii trials. Also maybe they try to conduct in subsaharan aferica where there are large spread rates among straights and disease is more endemic in populations.

Phase 1 is just a safety trial. Imagine how many years it will take to make a statistically sound conclusion of the efficacy rate?

People seem overly optimistic then. Phase 1 trials are only used to test the safety of the drug, nothing else. Not sure why they plan to take such a long time for this initial phase. Covid was just a couple of weeks.

If the initial stage is already 2 years, I don't see a Phase 3 trial taking less than 3 times that amount of time. It will be super difficult to test. The R0 value of HIV is relatively low.

Phase 1 just checks to see what is the highest dose that can be given without adverse effects. It does not test the effectiveness of the vaccine.

I assume the effectiveness of PrEP doesn't help the case, as infection can now be prevented for those at high risk.

Might be important to keep an eye out for PrEP access progression and these trails around the world...

What makes it so difficult?

At some point, somebody needs to be exposed to HIV with an unproven vaccine. Current design is just "give it to enough people to show they get HIV statistically lower than their origin populations.

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