The researchers found that over a 15 year time horizon, an average of 116,500 cases of clinical malaria disease and 484 deaths would be averted for every 100,000 children vaccinated under a four-dose schedule of immunizations at 6, 7.5, 9 and 27 months of age.
This translates to approximately 1.2 cases averted per vaccinated child and one malaria death averted for every 200 children vaccinated. These data apply to children living in regions of Africa that experience moderate to high malaria transmission, countries where prevalence rates for the most deadly malaria parasite, Plasmodium falciparum, range from 10 to 65 percent, and assumes a vaccine coverage rate at fourth dose of approximately 70 percent.
Melissa Penny from the Swiss Tropical and Public Health Institute said that they found that RTS,S vaccine would have significant impact on malaria disease in all but the lowest malaria transmission regions.
Penny noted that the numbers indicate that 6 to 29 percent of malaria deaths in children younger than age five could potentially be averted by the vaccine in the areas in which it is implemented, when used alongside other malaria control interventions.
As part of the modelling study, the authors considered a range of possible vaccine prices, from 2dollars to 10dollars. Compared to current malaria interventions, they found that the vaccine would be cost-effective to implement under an assumed price of USD 5 per dose in areas of moderate and high malaria transmission.
Among the limitations of the analysis noted by the researchers is remaining uncertainty in the vaccine efficacy after the four years of follow-up observed in the trial. They also noted that since the Phase III trial of RTS,S was not large enough to test for reduction in deaths from malaria (versus reduction in incidence of malaria cases) and the quality of care provided to participants was high, the modelling studies’ projection of deaths requires further validation during the implementation phase.