Mosquirix (RTS,S): a novel vaccine for the prevention of Plasmodium falciparum malaria

Abstract

Objective: To summarize and evaluate the literature for Mosquirix (RTS,S) and provide insight into the therapeutic and economic controversies of this novel malaria vaccine candidate.

Data sources: A systematic literature search was performed using the terms Mosquirix; RTS,S; malaria; vaccine; and Plasmodium in MEDLINE (1948-November 2011), EMBASE (1980-November 2011), International Pharmaceutical Abstracts (1970-November 2011), Google, and Google Scholar.

Study selection and data extraction: Clinical trials describing vaccine development, pharmacology, pharmacokinetics, efficacy, and safety were reviewed. For efficacy, clinical trials were reviewed that reported acquisition of malarial disease. Information regarding study design, population, study period, baseline characteristics, clinical outcomes, results, and assessors of quality was extracted.

Data synthesis: Five randomized controlled trials and 4 follow-up extension studies were identified. In Phase 2 trials, vaccine efficacy rates were 33-65% in infants and 30-53% in children for preventing the first episode of clinical disease. In Phase 3 trials, vaccine efficacy was 56% in children aged 5-17 months. RTS,S reduced the number of clinical malaria episodes and prevented severe malaria in several studies. The follow-up period for vaccine efficacy ranged from 6 to 45 months. RTS,S 25 μg is administered intramuscularly as 3 injections given 1 month apart for infants and children. RTS,S appears to be generally well tolerated. A few cases of meningitis and seizures (within 7 days of vaccination) have been reported.

Conclusions: RTS,S has demonstrated efficacy and safety in Phase 1, 2, and 3 trials, and has the potential to decrease morbidity and mortality from malaria worldwide. Major challenges include determination of the duration of immunity, assessment of its cost-effectiveness, its use in special populations, and its dissemination in endemic regions. Pending further studies, RTS,S has the potential to become the benchmark as the first effective vaccine against malaria.