- vaccines are typically developed against viruses and bacteria; malaria is caused by a parasite. vaccination against parasites is harder.
- TFA posits that, since the worst malaria strains mostly affect impoverished areas, there's less profit motive. I suspect this is true, but would love to see proof.
"Biologically, a protist-disease vaccine is more difficult to develop due to the mechanism and pathophysiology of diseases such as malaria and chagas."
More on vaccines for protozoal diseases:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3961066/
Specifics on the difficulty with a vaccine for malaria:
https://www.malariavaccine.org/malaria-and-vaccines/vaccine-...