New malaria vaccine ‘safe and well tolerated’ in trials
The jab targets parasites after they pass through the liver and into the blood, which is the stage that causes symptoms including fever and chills.
A new malaria vaccine that tackles the infection at a different stage to those currently on offer has been shown to be “safe and well tolerated” in clinical trials.
It is hoped the jab – known as RH5.1/Matrix-M – will “significantly reduce” the number of deaths and severe cases of the disease.
It targets malaria in the “blood stage”, which comes after the plasmodium falciparum parasite that causes the deadliest form of the disease passes through the liver.
Once red blood cells become infected, symptoms such as fever and chills begin, and can lead to complications including anaemia and organ failure.
Existing licensed jabs target the liver stage of malaria – which is symptomless – and are “very effective” at stopping parasites from getting into the blood, researchers said.
But if some “slip through the net”, existing jabs are not effective, experts said.
Angela Minassian, associate professor in the department of biochemistry, who leads the clinical blood-stage malaria vaccine programme at the University of Oxford, added: “Our goal, by targeting the blood stage of the disease with this vaccine, is to significantly reduce the number of severe cases and deaths.
“The current licensed vaccines, R21/Matrix-M and RTS,S/AS01, target the liver stage of the parasite and are very effective at stopping parasites from getting into the blood.
“However, if they fail and parasites slip through the net, disease will develop as these approved vaccines have no activity against malaria in the blood.
“Adding RH5.1/Matrix-M to these licensed vaccines should provide a vital second line of defence, achieving even higher levels of protection.
“Importantly, our study has provided the first real-world data to show that this type of vaccine works by reducing the level of parasites in the blood.”
The phase 2b trial involved 361 children, split into two groups.
One group received three doses of the RH5.1/Matrix-M vaccine and the other three doses of a rabies vaccine.
Those who had the RH5.1/Matrix-M developed high levels of antibodies against the malaria parasite, the study found.
This was more pronounced among children who had their jab as a newborn and at one and five months of age compared with those who had theirs as newborns and at one and two months.
Simon Draper, professor of vaccinology and translational medicine in the departments of paediatrics and biochemistry at the the Kavli Institute of Nanoscience, invented the RH5.1/ Matrix-M vaccine.
He said: “The development of an effective blood-stage malaria vaccine has proved to be an exceptionally tough scientific challenge, with previous clinical trials over a number of decades reporting no or minimal efficacy.
“These first efficacy results for a new generation of blood-stage vaccine candidates targeting the RH5 malaria protein are hugely encouraging, and represent a major milestone for the malaria field.
“We now have the exciting opportunity to test the new RH5.1 blood-stage vaccine in combination with the approved liver-stage vaccines, with the goal of developing a second-generation product that can offer very high-level efficacy against malaria disease in young African children.”
According to the World Health Organisation, the African region accounted for 94% of malaria cases, or 233 million, and 95% of deaths, or 580,000.
Children under the age of five accounted for about 80% of all malaria deaths in the region.
Halidou Tinto, a professor of parasitology and regional director of the Institut de Recherche en Sciences de la Sante (IRSS), based in Burkina Faso, said: “Frequent malaria infections can impair a child’s growth and development.
“This trial has shown that RH5.1/Matrix-M is safe and well tolerated. No serious side effects were reported, and further stages of the trial and follow-on trials will continue to monitor the vaccine’s longer-term safety and efficacy.”
