AIDS Vaccine research funding has $854 million, microbicide funding is $217 million. Why the disparity?

I am writing a paper on AIDS microbicides vs vaccines, and one issue I am having a hard time dealing with is the reason behind the huge disparity in funding for the two approaches to controlling the AIDS epidemic. Personally, it seems that a microbicide is more within reach at this time, so it should have more funding to quickly get it in the hands of women, especially in sub-Saharan Africa. However, a vaccine would obviously be the ideal answer.

Can you guys help with ideas on why this disparity exists? (almost 4 times more money goes to vaccine research than microbicide research). Who decides, and why did they allocate it this way?

Note: a microbicide is not a treatment--it's used to prevent HIV infection AFTER risky treatment. It's worthless once HIV has infected your T cells.

A cynical view is that any microbicides developed would be marketed toward resource poor communities - in other words there's less potential money to be made, and the drive to look for solutions with this approach comes mainly from the third world where there's less R&D money available.

A pharmaceutical company that develops an effective vaccine will be sitting on a gold mine till the patent runs out. There's less money to be made from a microbicide.

A less cynical view is the chances of developing an effective and reliable product. At present there are no proven reliable microbicides for sexually transmitted infections, although there are a number in the testing pipeline. By contrast there's already been some success in developing vaccines, including two for sexually transmissible infections (HPV and hep B), although a vaccine for HIV seems a long way off, if ever.

Interesting question, though.

[Additional] Predicting how far you are from the end of the pipeline is pretty difficult without some kind of precedent in the development process. Not that such predictions are always accurate: an "HIV vaccine within five years" was predicted as long ago as 20 years ago.

We don't have a great track record in microbicides effective in preventing the transmission of STIs, which have been used for centuries. None of them have yet been shown to work, and some, such as nonoxynyl 9, actually increase transmission. This can make it hard to argue a case that a particular product has a good enough chance of working to justify a clinical trial. Not imposible, but difficult.

An EFFECTIVE anti-HIV microbicide - reliable, easy to use and affordable to the target market would be a major breakthrough, but you shouldn't underestimate the difficulty of the task: no such microbicide has yet been developed for an STI.

Sexually transmitted infections pose unique problems for transmission blocking compared with infections passed on through water, or air or fomites. At present the best we have are physical barriers like condoms (or abstinence or other types of sexual behaviour change). I agree that vaccines might have figured dispropotionately as potential HIV transmission-prevention solutions. But we don't know, yet.

We won't know what the best answers are until we find them.

Because a vaccine would ultimately prevent someone from contracting HIV, but a microbicide wouldn't prevent someone from getting it, it would just help someone who already has it, and then if they are cured, they can always get it again, especially if they have a risky sexual behavior that doesn't change.

A vaccine for HIV that was actually only 30% effective would be immediately approved. Every attempt, and there have been a few, have been spectacular failures.

But the funding is there for it, so they'll continue to piss away money chasing a vaccine for something that was a mistake in the first place, just nobody wants to say so because, well, that would mean all these careers and all the work so many people with PhD's have been doing is a huge embarrassing farce, and nobody would want THAT now, would they ?

Also, there's the fact that past microbicides have also been a real mess. Nonoxynol-9 was in everything a few years back, and it turned out it actually INCREASED the spread of HIV when used during anal sex. Ooops ! So there's that little disaster. There have been others, what with the tendency to preserve microbicides with really nasty toxic chemicals.

Finally, I have to ask, why does anybody need 217 million dollars to come up with a microbicide ? Why is it so hard to do ? How much has already been spent, probably 10 times that, some people might wonder :

"Seriously... What The Hell ! 217 million for making toxic chemical concoctions to put on, in, and around our genitals ?"