I find these results extremely promising. If I understand the numbers correctly, about 450,000 children die of malaria alone every year. That means a 13% reduction in deaths would save over 50,000 children per year. This is a lower bound estimate as well, as there are other sources of child mortality and the 13% figure is for all deaths.
I think some of the other commenters were expecting higher numbers. It has been very difficult to produce a malaria vaccine in the past, and we already knew this particular one was not very effective. If you had this as a prior, you should be able to see this as the breakthrough it ultimately is.
13% is the reduction in all-cause mortality — ie, if every death this prevented was a death from malaria, this reduced deaths from malaria by over 99%.
One hypothesis is that some people who caught malaria but did not die from malaria, did die more frequently to another cause where having had malaria was a contributing factor to that death.
I think some of the other commenters were expecting higher numbers. It has been very difficult to produce a malaria vaccine in the past, and we already knew this particular one was not very effective. If you had this as a prior, you should be able to see this as the breakthrough it ultimately is.