Early research on an investigational malaria jab has sparked hopes of an effective vaccine against the disease, which kills more than 600,000 people every year.
Data from a Phase I trial, conducted by researchers at the National Institute of Allergy and Infectious Diseases and published in the journal Science, show that the PfSPZ Vaccine is safe, generates an immune system response, and offers protection against malaria infection in healthy adults.
The vaccine is composed of live but weakened sporozoites of the species Plasmodium falciparum, the most deadly of the malaria-causing parasites.
Just three of the 15 participants given higher dosages of the jab contracted the disease after being exposed to infected mosquitos, compared to 16 of 17 in the lower dosage group, the researchers said.
Given the huge global burden of the malaria, the World Health Organisation has called for the availability of a vaccine with 80% efficacy by 2025, as there is currently no protection against the disease.
"Scientists and health care providers have made significant gains in characterising, treating and preventing malaria; however, a vaccine has remained an elusive goal", noted NIAID Director Anthony Fauci, adding: "we are encouraged by this important step forward.”
Nevertheless, given the small size of the trial - which involved just 57 adults overall - larger-scale studies will be essential in determining whether the benefits of PfSPZ can be replicated in a wider population.
A number of follow-up studies are planned, including research on possible protection against other Plasmodium strains and the durability of protection, and the researchers may also evaluate whether higher doses administered subcutaneously or intradermally offer the same level of protection as that seen in this study.