Models Predict Positive Public Health Effects for RTS,S Vaccine — with Qualifications

Mary E. Wilson, MD reviewing Penny MA et al. Lancet 2015 Nov 5. Greenwood B and Doumbo OK. Lancet 2015 Nov 5.

The combined results of four models suggest high cost-effectiveness of the malaria vaccine over 15 years in areas with parasite prevalence >10%.

Phase III clinical trials of RTS,S/AS01 have shown modest vaccine efficacy against clinical malaria after three doses — 20% in infants (6–12 weeks) and 35% in children (5–17 months) during 32 months follow-up, with efficacy waning over time (NEJM JW Infect Dis Jun 2015 and Lancet 2015; 386:31). Given these results, should this vaccine be used and, if so, in which populations?

To examine the vaccine's cost-effectiveness and public health effects, researchers used estimates and predictions from four modeling groups. They quantified the potential number of cases and deaths averted over 15 years if vaccination is implemented, with a three- or four-dose vaccine schedule, for populations with parasite prevalence in 2- to 10-year-olds between 3% and 65%.

The models predicted that at 10% to 65% parasite prevalence, a median of 116,480 clinical cases and 484 deaths would be averted per 100,000 fully vaccinated children with the four-dose schedule. Little public health benefit was predicted at parasite prevalences <3%. The models disagreed on the additional public health effect for the fourth vaccine dose: Three predicted substantial benefit, and one found only a marginal effect. At a price of $5 per dose, the estimated cost was $87 ($43–$238) per disability-adjusted life-year averted.

Citation(s):

Penny MA et al. Public health impact and cost-effectiveness of the RTS,S/AS01 malaria vaccine: A systematic comparison of predictions from four mathematical models. Lancet 2015 Nov 5; [e-pub].

Greenwood B and Doumbo OK.Implementation of the malaria candidate vaccine RTS,S/AS01. Lancet 2015 Nov 5; [e-pub].