Final clinical trials of a malaria vaccine, the first to reach this stage, suggest it could help protect millions of children against malaria. But tests on 16,000 children found that booster doses were of limited use and vaccines in young babies were not effective. After children aged 5-17 months were given three doses of the vaccine, the immunisation was only 46% effective.
But experts say getting the vaccine this far is a scientific milestone. Data from the trial published in The Lancet showed that the success rate fell to even lower levels in younger infants. Scientists have been working on the vaccine for more than 20 years, but observers believe there is still a long way to go.
There is currently no licensed vaccine against malaria anywhere in the world. With around 1,300 children dying in sub-Saharan Africa from malaria every day, scientists say they are delighted to have got to this stage in developing a vaccine against a very clever parasite.