Research has shown that trial malaria vaccine are safe to generate an immune system response and to offer protection against malaria infection in healthy adults.
The early stage clinical test malaria vaccine research published in the Journal Science, used PfSPZ vaccine, which was developed by scientists at Sanaria Incorporated of Rockville, Maryland.
The study which was made available to the Ghana News Agency, noted that the clinical evaluation was conducted by researchers at the National Institute of Allergy and Infectious Diseases, as part of the National Institutes of Health (NIH), and their collaborators at the Walter Reed Army Institute of Research, Silver Spring- Maryland, and the Naval Medical Research Centre at Bethesda, Maryland.
It said malaria is transmitted to humans by the bite of an infected mosquito, leading to infectious malaria parasites.
In the immature, sporozoite stage of their life cycle, the parasite first travel to the liver, where they multiply, and then spread through the bloodstream, at which time symptoms develop.
According to the research, the PfSPZ vaccine is composed of live but weakened sporozoites of the species Plasmodium (P) falciparum, the most deadly of the malaria-causing parasites.
It said the Anopheles gambiae mosquito obtains a blood meal as it feeds on a human host.
The phase I trial, which took place at the NIH Clinical Centre in Bethesda, received informed consent from and enrolled 57 healthy adult volunteers from 18 to 45 years, who have never had malaria.
“Of these, 40 participants received the vaccine and 17 did not. To evaluate the vaccine’s safety, vaccines were split into groups receiving two to six intravenous doses of PfSPZ vaccine at increasing dosages.
“After vaccination, participants were monitored closely for seven days. No severe adverse effects associated with the vaccine occurred and no malaria infections related to vaccination were observed,” it stated.
Based on blood measurements, researchers found that participants who received a higher total dosage of PfSPZ vaccine generated more antibodies against malaria and more white blood cells — a type of immune system cell — specific to the vaccine.
It said, to evaluate whether and how well the PfSPZ vaccine prevented malaria infection, each participant — the vaccinees as well as the control group that did not receive vaccine – was exposed to bites by five mosquitoes carrying the P. falciparum strain, from which the PfSPZ vaccine was derived.
The statement said: “This controlled human malaria infection procedure — a standard process in malaria vaccine trials — took place three weeks after participants received their final vaccination.
“Participants were monitored as outpatients for seven days and then admitted to the NIH Clinical Centre, where they stayed until they were diagnosed with malaria, treated with anti-malarial drugs and cured of infection, or shown to be free of infection.”
The researchers found that the higher dosages of PfSPZ vaccine were associated with protection against malaria infection.
“Only three of the 15 participants who received higher dosages of the vaccine became infected, compared to 16 of 17 participants in the lower dosage group who became infected.
“Among the 12 participants who received no vaccine, 11 participants became infected after mosquito challenge.
“An important challenge in the continued development of PfSPZ vaccine is that the vaccine currently is administered intravenously — a rare delivery route for vaccines,” it said.
There were an estimated 219 million cases of infection in 2010, the World Health Organisation reports, including 660,000 deaths. 90 per cent of those deaths occurred in Africa, mostly among children younger than five years old.
About 3.3 billion people worldwide are at risk of contracting the disease with people living in the poorest countries as the most vulnerable.