Was the First Malaria Vaccine Tested in 1898?

Early trials of killed, whole-cell typhoid vaccine indicated a paradoxical, positive effect on malaria infections. British soldiers in India in 1898 reported > 90% decrease in malaria recurrences after receiving an investigational typhoid vaccine despite no intention or expectation to observe such an outcome. In the 1940s, multiple doses of intravenous typhoid vaccine appeared to control parasitemia and limit reinfection in three syphilis patients purposefully infected with Plasmodium vivax. Several modern vaccines (against human papillomavirus, hepatitis B virus, and malaria) use a detoxified lipid A derived from Salmonella as an immune adjuvant. Early typhoid vaccines could have plausibly functioned as an innate immune stimulus, leading to some protection against malaria.