Final clinical trials of a malaria vaccine – the first to reach this stage – suggest it could help protect millions of children against malaria. But, reports BBC News, tests on 16,000 children from seven African countries 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 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.
RTS,S/AS01 is the first malaria vaccine to reach advanced trials and show any sign of working in young children. 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.
Professor Brian Greenwood, study author and professor of clinical tropical medicine at the London School of Hygiene and Tropical Medicine, said he was "a little disappointed" by the results of the clinical trials. "I hoped the vaccine would be more effective, but we were never going to end up with the success seen in measles vaccines with 97% efficacy." That is because the malaria parasite has a complicated life cycle and it has learnt how to evade the immune system over hundreds of years.
The vaccinations took place at 11 sites across Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique and Tanzania. The trials found the vaccine's ability to protect children gradually waned over time. Scientists tried to bolster this with a booster, but protection never reached the level provided by initial doses. The clinical trials also found that meningitis occurred more frequently in children given the vaccine.
However, Greenwood said the data was very robust and the vaccine could still reduce attacks of malaria by around 30%. The European Medicines Agency will now review the data and, if it is satisfied, the vaccine could be licensed. And the World Health Organisation could then recommend its use in October this year.
[link url="http://www.bbc.com/news/health-32437383"]Full BBC News report[/link]
[link url="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(15)60721-8/abstract"]The Lancet article[/link]