It's not regardless of the vaccine, though. You'd expect child mortality to go down year by year because of things like that. There used to be malaria in the UK, I'm sure child mortality dropped when it died off here too.
> To calculate mortality in the three countries, where death registry statistics are unreliable, the researchers employed tens of thousands of community reporters—more than 14,000 of them in Kenya alone—to conduct household surveys of childhood deaths in 79 areas where the RTS,S vaccine was administered and 79 comparator areas where it was not available.
If the group that got the vaccine has a 13% lower all cause mortality than the group that didn’t, and it was your standard randomized controlled double blind study, that’s a huge win.