In late 2012, the World Health Organization (WHO) published an update of the “Rainbow Tables,” which identified more than two dozen active malaria vaccine candidates in clinical development (human testing) and more than a dozen in preclinical development. The vast majority of candidates in clinical development targeted Plasmodium falciparum, with roughly equal numbers targeting the blood and pre-erythrocytic stages of the malaria parasite.

Unlike the situation two years ago, however, at least one transmission-blocking candidate was reported to be in clinical testing. The Rainbow Tables reported only one vaccine candidate in large-scale, late-stage testing, namely the RTS,S candidate under development by GlaxoSmithKline Vaccines (GSK), the PATH Malaria Vaccine Initiative (MVI), and research centers in seven African countries.