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| ISV Paper of the Month |
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November 2011 |
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First Results of Phase 3 Trial of RTS,S/AS01 Malaria
Vaccine in African Children |
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The RTS,S Clinical Trials Partnership |
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N Engl J Med 2011; 365:1863-75 |
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An ongoing phase 3 study of the efficacy, safety, and
immunogenicity of candidate malaria vaccine RTS,S/AS01 is being conducted in seven
African countries. |
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From March 2009 through January 2011, we
enrolled 15,460
children in two age categories — 6 to 12 weeks of age and 5 to 17 months of age
— for vaccination with either RTS,S/AS01 or a non-malaria comparator vaccine. The
primary end point of the analysis was vaccine efficacy against clinical malaria
during the 12 months after vaccination in the first 6000 children 5 to 17 months
of age at enrollment who received all three doses of vaccine according to protocol.
After 250 children had an episode of severe malaria, we evaluated vaccine efficacy
against severe malaria in both age categories. |
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In the 14 months after the first dose of vaccine, the
incidence of first episodes of clinical malaria in the first 6000 children in the
older age category was 0.32 episodes per person-year in the RTS,S/AS01 group and
0.55 episodes per person-year in the control group, for an efficacy of 50.4% (95%
confidence interval [CI], 45.8 to 54.6) in the intention-to-treat population and
55.8% (97.5% CI, 50.6 to 60.4) in the per-protocol population. Vaccine efficacy
against severe malaria was 45.1% (95% CI, 23.8 to 60.5) in the intention-to-treat
population and 47.3% (95% CI, 22.4 to 64.2) in the per-protocol population. Vaccine
efficacy against severe malaria in the combined age categories was 34.8% (95% CI,
16.2 to 49.2) in the per-protocol population during an average follow-up of 11 months.
Serious adverse
events occurred with a similar frequency in the two study groups.
Among children in the older age category, the rate of generalized convulsive seizures
after RTS,S/AS01 vaccination was 1.04 per 1000 doses (95% CI, 0.62 to 1.64). The
RTS,S/AS01 vaccine provided protection against both clinical and severe malaria
in African children. (Funded by GlaxoSmithKline Biologicals and the PATH Malaria
Vaccine Initiative; RTS,S ClinicalTrials.gov number, NCT00866619.) |
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