1. The R21/Matrix-M vaccine had a high 12-month efficacy across seasonal and standard sites.

2. The reduction in malarial infection rates was 4 times greater at seasonal sites compared to standard sites.

Evidence Rating Level: 1 (Excellent)

Study Rundown: The R21/Matrix-M vaccine is a novel vaccine for the prevention of Plasmodium falciparum infection in regions with moderate to high malaria transmission. In a recent phase 2b trial, the vaccine demonstrated high efficacy against clinical malaria with seasonal administration. This randomized controlled trial aimed to assess the efficacy of R21/Matrix-M vaccine against clinical malaria among 4800 African children. The primary outcome was vaccine efficacy from 2 weeks after the third vaccination to one year after completion of the primary series, while a key secondary outcome was vaccine efficacy against severe malaria. According to study results, R21/Matrix-M was well tolerated and demonstrated high efficacy across standard sites after the 12-month follow-up period.

Click to read the study in The Lancet

Relevant Reading: Seven-Year Efficacy of RTS,S/AS01 Malaria Vaccine among Young African Children

In-depth [randomized-controlled trial]: Between Apr 26, 2021, and Jan 12, 2022, 5477 patients were assessed for eligibility across 5 sites in Africa. Included were patients aged 5-36 months with no contraindications to the R21/Matrix-M vaccine. Altogether, 4644 patients (3103 in R21/Matrix-M group and 1541 in the control group) were included in the modified per-protocol analysis. The primary outcome of the study revealed a 12-month vaccine efficacy of 75% (95% confidence interval [CI] 71-79, p<0.0001) at the seasonal sites and 68% (95% CI 61-74, p<0.0001) at the standard sites for time to first clinical malaria episode. The vaccine also demonstrated a strong rate reduction (868 cases per 1000 children-years at seasonal sites and 296 cases per 1000 children-years at standard sites) with good efficacy against multiple clinical malaria episodes (75% for seasonal and 67% for standard sites). Findings from this study suggest that the R21/Matrix-M vaccine offers significant protection against clinical malaria in African children.

Image: PD

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