GlaxoSmithKline is ready to file the world's first malaria vaccine after follow-up data from a large-scale trial in Africa confirmed its ability to prevent the disease.

The drug giant said it plans to file RTS,S - the most clinically advanced malaria vaccine candidate - with the European Medicines Agency in 2014, which means it could be in use by 2015 if approval is granted.

The move comes on the back of clinical data showing that, overall, RTS,S almost halved the number of malaria cases in young children (aged five-17 months at first vaccination) and cut by around a quarter the malaria cases in infants (aged six-12 weeks at first vaccination).

Vaccine efficacy was also assessed separately at each of the trial sites, and was found to be statistically significant at all sites in young children and at four in infants, the firm said.

The efficacy and public health impact of RTS,S were assessed in the context of existing malaria control measures, such as insecticide treated bed nets, which were used by 78% of children and 86% of infants in the trial. 

After 18 months' follow-up, children aged five-17 months at first vaccination with RTS,S experienced 46% fewer cases of clinical malaria, compared to children immunised with a control vaccine. 

An average of 941 cases of clinical malaria were prevented over 18 months of follow-up for every 1,000 children vaccinated in this age group, while severe malaria cases were reduced by 36% and malaria hospitalisations were cut 42%.

Those aged six-12 weeks at first vaccination with RTS,S had 27% fewer cases of clinical malaria. Over 18 months of follow-up, 444 cases of clinical malaria were prevented for every 1,000 infants vaccinated. However, the reduction of severe malaria cases and malaria hospitalisations by 15% and 17%, respectively, were not statistically significant.

Efficacy wanes over time

It was also found that, overall, vaccine efficacy declined over time; previous data from one-year follow-up showed efficacy of RTS,S was 56% against clinical malaria and 47% against severe malaria for the five-17 month-old age group, and 31% and 37% in the six-12 week-old age group, respectively.

Nevertheless, GSK's chief executive Sir Andrew Witty stressed that, "while we have seen some decline in vaccine efficacy over time, the sheer number of children affected by malaria means that the number of cases of the disease the vaccine can help prevent is impressive".

"While we want to be careful about not getting ahead of the data, this trial continues to show that a malaria vaccine could potentially bring an important additional benefit beyond that provided by the tools already in use," added David Kaslow, vice president of product development at non-profit organisation PATH, which is developing the vaccine with GSK with help from the Bill and Melinda Gates Foundation.

Data also showed that RTS,S continued to display an acceptable safety and tolerability profile. It was previously reported that meningitis was observed more frequently in the malaria vaccine group, though it was considered unlikely to be vaccine-related. Still, GSK stressed that the occurrence of meningitis "will be followed closely during the remainder of the trial".