A Cochrane review [Abstract] 1 included ten studies with a total of 9 698 subjects. The object was to assess the effect of SPf66 malaria vaccines (one of the earliest vaccines developed) against Plasmodium falciparum, P. vivax, P. malariae, and P. ovale in preventing infection, disease, and death. Results with SPf66 in reducing new episodes of P. falciparum malaria were heterogeneous: it was not effective in four African trials (RR 0.98, 95% CI 0.90 to 1.07; 2 371 participants) or in one Asian trial (RR 1.06, 95% CI 0.90 to 1.25; 1 221 participants). In four trials in South America the number of first attacks with P. falciparum was reduced by 28% (RR 0.72, 95% CI 0.63 to 0.82; 3 807 participants). It did not reduce episodes of P. vivax malaria or admission to hospital with severe malaria. Trials have not indicated any serious adverse events with SPf66 vaccine.
Another Cochrane review 2 (abstract , review [Abstract]) included nine studies with a total of over 3 000 subjects. The object was to assess the efficacy and safety of pre-erythrocytic malaria vaccines against any type of human malaria. In semi-immune children, RTS,S vaccine reduced clinical episodes of malaria by 26% (95% CI 13% to 37%) and severe malaria by 58% (95% CI 15% to 79%) for up to 18 months. Prevalence of parasitaemia was also reduced by 26% (95% CI 11% to 38%) at six months after immunization. RTS,S also reduced clinical malaria episodes by 63% (95% CI 18% to 83%) in semi-immune adult men in the second year of follow up after a booster dose. No severe adverse events were judged to be related to RTS,S vaccine, although the frequencies of injection site pain, swelling, arm motion limitation, headache, and malaise were increased in the vaccine groups. There was no evidence for effect of the CS-NANP vaccines (307 participants, 3 trials), CS102 peptide vaccine (14 participants, 1 trial), or the ME-TRAP vaccine (372 participants, 1 trial).
Another Cochrane review 3 (abstract , review [Abstract]) included five studies with a total of 217 subjects. The objective was to assess the effect of blood-stage malaria vaccines in preventing infection, disease, and death. Several such vaccines are under development, but only one (MSP/RESA, also known as Combination B) has been tested in randomized controlled trials. No severe or systemic adverse effects were reported at MSP/RESA doses of 13 to 15 µg of each antigen (39 to 45 µg total). One small efficacy trial with 17 non-immune participants with blood-stage parasites showed no reduction or delay in parasite growth rates after artificial challenge. In the second efficacy trial in 120 children aged five to nine years in Papua New Guinea, episodes of clinical malaria were not reduced, but MSP/RESA significantly reduced parasite density only in children who had not been pretreated with an antimalarial drug (sulfadoxine-pyrimethamine). Infections with the 3D7 parasite subtype of MSP2 (the variant included in the vaccine) were reduced (RR 0.38, 95% CI 0.26 to 0.57; 719 participants) while those with the other main subtype, FC27, were not (720 participants).
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