Results from P. vivax vaccine efficacy trials VAC071 and VAC079 published in Science Translational Medicine

Our group has published the results from our P. vivax vaccine efficacy trials VAC071 and VAC079 in Science Translational Medicine, which made the cover of that issue. The trials tested two different formulations of vaccines targeting the P. vivax Duffy-binding protein - a viral vectored formulation and a protein and adjuvant formulation. The trials showed that the protein vaccine given in a delayed dosing regimen, where the third dose of the vaccine was given at around one year, was able to inhibit parasite growth in blood by around 50% during controlled human malaria infection. The delayed dosing regimens were a result of the trials being halted during the Covid-19 pandemic and were a silver lining to the disruptions caused by the pandemic to these trials. 

Our paper also featured in a news article by the New Scientist: https://institutions.newscientist.com/article/2382295-malaria-vaccine-shows-promise-against-relapsing-form-of-the-disease/

Access to the full text of the article can be found here: https://www.science.org/stoken/author-tokens/ST-1317/full, as well as via our Publications page.

Hou, Mimi M., Jordan R. Barrett, Yrene Themistocleous, Thomas A. Rawlinson, Ababacar Diouf, Francisco J. Martinez, Carolyn M. Nielsen, et al. "Vaccination with Plasmodium Vivax Duffy-Binding Protein Inhibits Parasite Growth during Controlled Human Malaria Infection." Science Translational Medicine.

There are no licensed vaccines against Plasmodium vivax. We conducted two phase 1/2a clinical trials to assess two vaccines targeting P. vivax Duffy-binding protein region II (PvDBPII). Recombinant viral vaccines using chimpanzee adenovirus 63 (ChAd63) and modified vaccinia virus Ankara (MVA) vectors as well as a protein and adjuvant formulation (PvDBPII/Matrix-M) were tested in both a standard and a delayed dosing regimen. Volunteers underwent controlled human malaria infection (CHMI) after their last vaccination, alongside unvaccinated controls. Efficacy was assessed by comparisons of parasite multiplication rates in the blood. PvDBPII/Matrix-M, given in a delayed dosing regimen, elicited the highest antibody responses and reduced the mean parasite multiplication rate after CHMI by 51% (n = 6) compared with unvaccinated controls (n = 13), whereas no other vaccine or regimen affected parasite growth. Both viral-vectored and protein vaccines were well tolerated and elicited expected, short-lived adverse events. Together, these results support further clinical evaluation of the PvDBPII/Matrix-M P. vivax vaccine.