Efficacy and immunogenicity of RTS,S/AS01 and R21/Matrix-M malaria vaccines: - Systematic review and meta-analysis

Malaria is one of the most concerning issues of public health. Despite efforts in vector control and chemoprevention, it continues to remain a burden, and hence, a vaccine for malaria has the potential to reduce the overall parasite reservoir. Several types of vaccines have been developed; however, the two most novel ones are RTS,S/AS01 and R21/Matrix-M. The purpose of this study was to evaluate and compare the efficacy and immunogenicity of the two currently available malaria vaccines.

A literature search was carried out on PubMed, Scopus, and Cochrane databases searching for studies published between 2000 and 2024. After duplicate removal, 832 records were screened and 60 were selected for full-text screening, after which 8 were included in our final review, as they were eligible based on our inclusion and exclusion criteria.

This systematic review and meta-analysis showed that the RTS,S/AS01 malaria vaccine provides significant protection in the 6-12-week age group, with a 23.0% malaria risk reduction and risk ratio (RR) of 0.77. In the 5-17-month age group, the RR for malaria risk reduction was 0.61 for both vaccines; the efficacy declined over time, showing the importance of a booster dose and how RTS,S/AS01 vaccines were safe and generated a strong antibody response across age groups. In comparison, R21 displayed high efficacy with a low event rate of 0.22 and a strong antibody response, but more frequent adverse events.

As compared to prior reviews, our study highlights that both of the two breakthrough vaccines are paving the way for total malaria elimination and reduction in morbidity and mortality.