Malaria Vaccine Report: Hope on the Horizon?

Where malaria occurs (cdc.gov)

Here is a study recently published in the New England Journal of Medicine on the "RTS,S/AS01" vaccine against malaria.

Malaria, a parasitic disease carried by mosquitoes that destroys red blood cells, is still a major cause of worldwide morbidity and mortality (responsible for over 600,000 deaths per year) and an anti-malaria vaccine has been seen by many as the 'holy grail' of public health.

This study follows up one published in 2011 that noted a vaccine efficacy of 45% (95% CI 23.8-60.5) for severe malaria in children aged 5-17 months. The current trial looked at vaccine efficacy for children 6 to 12 weeks of age and found a much lower (not statistically significant) efficacy of 26% for cases of severe malaria in the intention-to-treat analysis (95% CI -7.4 to 48.6). 

Malaria parasites in red blood cells (cdc.gov)

Why the difference in efficacy between the two age groups? The authors posit the lower efficacy rate in younger children may have been due to a less mature immune system or to co-administration with other vaccines. 

Why has creating a malaria vaccine proved so elusive? In a nice editorial that accompanies the above article, Johanna Daily outlines some of the challenges we have encountered to date in creating a malaria vaccine. These include malaria's long coevolution with humans, which has produced a robust parasite that is adept at avoiding destruction by our immune system, as well as an incomplete understanding of our immune response to the organism (which would provide insight into vaccine development). 

Of note, malaria is another organism where drug resistance is a major problem. Given the serious, life-threatening nature of malaria infections, and the paucity of drugs available to treat these, malaria drug resistance is a major global problem. 

Although the RTS,S/AS01 vaccine does not appear to be "ready for prime time," it does provide hope that an effective malaria vaccine can be produced. Given the global morbidity and mortality associated with this disease, continued intense research into malaria vaccine development is warranted.