Each date resolves YES if Malaria has been declared eradicated by the WHO (or an equivalent declaration by an appropriate organization of similar status if N/A) before Jan 1st of that year.

With regards to ambiguity of resolution my intent with this market is: "the time at which there has been a period of no recent Malaria deaths and a reasonable expectation of no further deaths in future, as declared by an authoritative organisation" and I will seek the most objective way of defining that.

The WHO's declaration of Smallpox eradication in 1980 would be analogous.