Vector-borne illnesses have doubled over the past two decades, as the number of pathogens grows and affected areas expand.
Vaccine effectiveness at 1 year was 75% at seasonal sites and 68% at standard sites for time to first malaria infection.
The first patients to receive the vaccine were a pair of twin babies.
In November, Cameroon said it would receive 331,200 doses of the RTS,S vaccine, which is produced by GSK.
The step clears the way for a broader rollout of R21/Matrix-M, which the WHO recommended in October.
Catastrophic flooding in Pakistan last year led to a fivefold jump in cases.
Cameroon is set to receive 331,200 doses of RTS,S, and four other African nations will receive 1.7 million doses in the coming weeks.
Bangladesh eliminated visceral leishmaniasis, Maldives interrupted leprosy transmission, and South Korea eliminated rubella.
Longer transmission seasons and migration of mosquitoes to new latitudes threaten to undo years of progress.
The WHO estimates malaria kills one child under age 5 every minute.