In 2005 Bill Gates launched the Grand Challenges in Global Health initiative to fund radical new ideas that could tackle the biggest problems in global health.
But, although the initiative was successful in highlighting the role of science in saving lives, it has taken much longer to achieve concrete results, Gates admits. It takes a long time to get an idea through clinical trials and low-cost manufacturing and ultimately to be accepted in developing countries.
I thought some [ideas] would be saving lives by now, and it'll be more like in ten years from now ... We were naive when we began, Gates says.
One example is the quest for vaccines that do not need refrigeration.
Back then, I thought: 'Wow we'll have a bunch of thermostable vaccines by 2010.' But we're not even close to that. I'd be surprised if we have even one by 2015.
Initially Gates gave US$450 million to 43 out of 1,600 submitted proposals in five-year grants. In 2007 he changed the strategy to fund more ideas with less money for each and started giving out hundreds of US$100,000 grants.
As a scientist in a developing country you can do a lot with $100,000, he says.
But two-thirds of these grants never get renewed. They fail scientifically or because of other obstacles.
For example, with rising ethical standards, clinical trials on illiterate people in poor countries have become more expensive and time-consuming. Regulatory authorities and decision-makers in the developing world are also more cautious about accepting new technologies from the West, because of fears of being misused by Western scientists.
So although a wide range of novel technologies has been developed, some face further challenges before their scale-up for use in real world would make sense.
Others seem to work well and have attracted funding from other sources.
Some of these new ideas that are at various development stages include: a single, hand-held diagnostic laboratory for a range of diseases; molecules to block mosquitoes' sense of smell, which they use to detect humans; and bio-fortified bananas and cassava.