Bill and Melinda Gates back an implant that could prevent HIV

You don't have to wait until after an infection to fight HIV. A technique known as pre-exposure prophylaxis has you taking preemptive medicine on a regular basis, greatly reducing the chances that HIV will take root in the first place. Needless to say, such a treatment could change the world if done well -- and the Bill & Melinda Gates Foundation wants to make sure that it's as easy as possible. They're investing $140 million in an Intarcia Therapeutics program that will develop an under-the-skin pump implant (you're looking at it above) that will deliver a steady stream of anti-HIV drugs in 6- or 12-month batches. Instead of having to remember to take medicine every day, you'd only have to top up once or twice a year.

There's also a variant of the pump targeted at type 2 diabetes. Intarcia started the paperwork on commercial use in November, so you could see it in use relatively soon.

Any practical implementation of the HIV pump is years away. Intarcia still has to settle on a drug to use, and there are regulations and similar hurdles to clear before it's ready to use. If it's deployed as promised, though, it could go a long way toward reducing the influence of HIV and AIDS in places like sub-Saharan Africa, where the virus remains a serious problem. Like with many medicines, the biggest challenge is simply getting people to take preventative drugs on a consistent basis -- this would make it much less of a hassle. Cost is still a concern (will the medicine be inexpensive enough that wide distribution is practical?), but the technology is at least in place.