Background

Among Indonesia’s 270 million people, over 150 million live at risk of malaria caused by any one of the five Plasmodium species known to cause this infection in humans – P. falciparum, P. vivax, P. malariae, P. ovale, and P. knowlesi. Endemic malaria transmission occurs on every major island of Indonesia, with stable endemic malaria dominating the vast undeveloped rural areas across the archipelago, being especially severe in the relatively impoverished and isolated eastern half of Indonesia.

The Indonesian Army deployment of malaria-naïve (or minimally malaria-exposed) infantry soldiers to Papua are highly exposed and vulnerable to severe forms of clinical malaria. The ideal intervention against this serious problem would be an effective vaccine that induces high-level, long-term sterilizing immunity to malaria infection. Preventing infection would also block onward transmission, and if administered to the majority of a population nearing malaria elimination, it may serve as the final intervention before genuine elimination is achieved.

This is the first trial of the malaria vaccine in a natural setting outside of Africa in several decades. It is also the first trial of the vaccines evaluated against natural strains of P. falciparum outside of Africa and, perhaps quite importantly, also against natural strains of P. vivax anywhere.

Aims

The clinical trial is a critical part of the PfSPZ-based vaccine development program. It will constitute the first head-to-head assessment of the two vaccine products (PfSPZ Vaccine and PfSPZ-CVac) for the prevention of naturally transmitted malaria in the field.

This trial aims to assess the safety, tolerability and immunogenicity of PfSPZ Vaccine and PfSPZ-CVac compared to placebos for each in Indonesian soldiers deployed to highly malarious northeastern Papua, Indonesia. The trial will also assess the vaccine efficacy (VE) of PfSPZ Vaccine and PfSPZ-CVac against first clinical malaria cases caused by P. falciparum (Pf) identified by thick blood smear microscopy in naturally exposed Indonesian soldiers. Secondary endpoints include the VE of each product against both patent and latent P. vivax malaria.

Outputs to date

As of October 2022, the study has completed its pre-exposure period that included the screening and immunization phase (approximately 26 weeks since SIV). Among 342 participants immunized with three doses of either PfSPZ Vaccine or PfSPZ C-Vac, 337 were deployed to Papua on 26 Sep 2022. RA inspection was completed on the first week of September. The exposure period will begin upon the soldiers’ arrival in Papua at mid or end of October 2022 and will last for nine months.