Currently available malaria vaccines are not yet sufficiently effective, but new vaccines show promise in early tests.
Many malaria vaccines are under development. Four of these have been tested against the most severe form of malaria, Plasmodium falciparum. The SPf66 vaccine against the blood stages showed a small effect in some studies, but not in Africa. Another vaccine (MSP/RESA) did not prevent malaria attacks, but meant the density of parasites in the blood was lower. Two vaccines aiming to prevent infection before it reaches the blood stream have also been tested. One had no effect, and one (the RTS,S vaccine) delayed infection and reduced clinical episodes of malaria in the second year after vaccination.