RTS,S/AS01 is the most sophisticated malaria vaccine at the moment, although it only gives partial, short-term protection. It was created for use in the expanded immunization program (EPI) for African youngsters. Another possible use would be to incorporate mass RTS,S/AS01 vaccination into the integrated malaria eradication plan in the Greater Mekong Subregion (GMS), where multidrug-resistant P.falciparum strains have developed and spread. Prior to testing RTS,S/AS01 in large-scale studies, the researchers determined whether the vaccine is safe and immunogenic in Asian people when delivered with and without antimalarial medicines. An open-label, randomized, controlled phase 2 study was carried out in Thai adults who were in good health. Standard enzyme-linked immunosorbent assays were used to assess antibody titres against PfCSP full-length (NANP) 6, PfCSP anti-C–term, and PfCSP full-length. Piperaquine, primaquine, and carboxy-primaquine concentrations were determined using liquid chromatography. A total of 193 individuals were enlisted in the trial, with 186 completing the 6-month follow-up period. All research subjects have seroconverted to the PfCSP 6, and the PfCSP Full Length, one month after the previous immunization. More than 90% of respondents had switched to the Pfanti-C-Term CSP. There was no evidence that vaccination regimens or medication regimens impacted drug concentrations or antibody levels. There were no severe adverse events associated with the trial treatments.
In a healthy adult Asian population, RTS,S/AS01 with and without dihydroartemisinin-piperaquine with a single low dose primaquine was shown to be safe and immunogenic.