The first results of the RTS,S vaccine already appeared in 1998 in a scientific paper. The conclusion was: Immune responses did not correlate with protection. Further optimization in vaccine composition will be required to induce longer-lasting protective immunity.
Stoute JA, Kester KE, Ballou Wr. Long-term efficacy and immune
responses following immunization with the RTS,S malaria vaccine.
J Infect Dis. 1998 178(4), 1139-44
Another randomised trial of the efficacy of RTS,S against natural P. falciparum infection in semi-immune adult...