Malaria is still one of the largest risks to health faced by humanity, with half the world’s population considered at risk from this disease. Transmitted by the Plasmodium falciparum parasite via mosquitoes, malaria infected over 210 million people in 2015, and caused almost 440,000 deaths. Tragically, African children under the age of five made up a significant proportion of the fatalities. To counteract this, a number of researchers around the world are trying to develop vaccines that offer long-term protection, benefiting locals and travellers alike.
As reported by the National Institute of Health (NIH), Sanaria Inc., based in Maryland, is working with the National Institute of Allergy and Infectious Diseases (NIAID) on a series of clinical trials. Using weakened P. falciparum sporozoites, the research team created a live vaccine that delivered promising short term results. Following this up, Dr Robert A. Seder and a team of NIAID researchers assessed if the PfSPZ Vaccine could protect people for longer periods.
Using healthy adults aged between 18 and 45, the study separated subjects into two groups, one receiving the PfSPZ vaccine, and one acting as a control. The researchers tested if the number of vaccinations influenced the level of protection, and if intramuscular injections were as effective as intravenous administrations.
To assess the vaccine’s short term protection, the research team exposed participants to bites from infected mosquitoes after three weeks. The results suggested that higher doses of the vaccines offer better protection, and intramuscular injections are much less effective.
Follow up tests to assess long term protection exposed subjects to bites at between 21 and 25 weeks after vaccination. Just over half of the subjects developed no sign of parasites in their blood. A smaller group were exposed after 59 weeks and, interestingly, showed no sign of parasite infestation in their blood. This suggests that the PfSPZ Vaccine may provide protection for over a year.
With no side effects apparent, research continues and the team are testing higher doses over longer periods, and against other strains of the P. falciparum parasite. This promising new vaccine could reduce child mortality in areas with endemic malaria and lead to significant improvements in life expectancy.