“There are not many scientists who have this incredible opportunity to work on a project and see the realization of that work being transformed into a vaccine that could save hundreds of thousands of lives,” says Cohen, who with his baggy cords, beard and mop of grey hair strikes a contrast with Witty’s clean-cut corporate look. “My worst nightmare is that it sits on the shelf for years.”

CONVINCING THE FUNDERS

Whether that happens will depend on securing funding and, crucially, how much the vaccine costs - a figure health care experts and donors would love to know. GSK has promised it will be cheap, with a profit margin of 5 percent over the cost of making it to be reinvested in new vaccines for malaria and other neglected diseases.

“The last thing in the world we want to do is get to 2014 or 2015, have something that is the world’s first vaccine to work against a parasite … and then say I’m sorry we couldn’t figure out a way to make it cheap enough for people in Africa to actually get it,” says CEO Witty.

But the company has yet to give an exact figure to enable direct comparison with, say, the cost of insecticide-treated mosquito nets - currently available for around $5 each. Witty points out that mosquito nets typically last around 20 washes, or three to four years, while a vaccine may last a lot longer. “We want a safe and effective vaccine … that complements, rather than replaces all the other things that are going on, and that will be priced in that kind of world.”

The uncertainty on price is one of the reasons for the debate about how, where and on what scale the new vaccine - designed exclusively for children in Africa - should be used. The cost-benefit analysis that donors must make when they work out where to spend their money is sure to be a lot more complex with this vaccine than with those targeting other diseases such as polio and smallpox. For those diseases, vaccines virtually guarantee (or guaranteed, in the case of smallpox, which was eradicated in 1979) people won’t get sick. With malaria, the picture is more complex, given its transmission cycle via mosquitoes and the practical steps that can already be taken to reduce the risk of infection.

“This is not the elimination or eradication vaccine,” says David Brandling-Bennett, deputy director for malaria at the Bill & Melinda Gates Foundation, which said last January it planned to spend $10 billion over the next decade researching new vaccines and bringing them to poor countries. “And obviously the situation with malaria is very different from the situation with smallpox which relied on a single tool - a highly effective vaccine that provided solid protection to essentially everyone who had it. We don’t have that yet for malaria, and we’re under no illusion that we do.”

Other vaccines in the pipeline are 10 years away or more. PATH Malaria Vaccine Initiative (MVI), a non-profit organization based just outside Washington D.C. that has channeled more than $200 million in grants from the Gates Foundation into the GSK vaccine (alongside more than $300 million from the drugmaker itself), has a long-term goal of developing a vaccine that is at 80 percent effective by 2025.

One candidate could be an amended version of the current GSK shot, which the drugmaker has started work on with Dutch biotech company Crucell (now the target of a $2.3 billion takeover bid from Johnson & Johnson). This would use a common cold virus to “prime” the immune system to get a stronger response, but it is still a year or so away from starting clinical trials. MVI has also just signed a deal with Merck & Co for a new vaccine project designed to stop the malaria parasite from entering the liver.

Experience shows it won’t be easy. Sanaria, a start-up biotech company with funding from MVI, recently found its experimental vaccine protected only five out of 80 volunteers in its first clinical trial. The Maryland-based firm is not giving up but its disappointing results demonstrate the scale of the challenge.