vaccine against malaria is close to becoming a reality. A few days ago a clinical trial was published in the journal MiddleWhere they confirm that the vaccine appears to be safe and favors an immune response in African infants, one of the groups most vulnerable to severe malaria.
Currently, there is only one vaccine against malaria approved by the World Health Organization, RTS,S. Provides partial protection from disease. However, results from a phase IB trial in Tanzania have shown that targeting Rh5 – a protein that the malaria pathogen Plasmodium falciparum uses to invade red blood cells – may generate a promising immune response that is effective in infants. more pronounced in groups.
“For prevent disease, Antisporozoite vaccines such as RTS,S should be 100% effective in preventing the parasite from invading the liver,” explains lead author and clinical scientist Angela Minassian from the University of Oxford, UK.
“Although Once a single parasite enters the trap, it will multiply in the liver.it will move into the bloodstream and infect red blood cells, where it will multiply rapidly,” he adds. Vaccinating a blood stage like Rh5 provides a second line of defense once the parasite enters the bloodstream, thereby Malaria gets a second chance to stop before the disease develops.”
A person gets infected with malaria by the bite of an infected mosquito, which releases ‘Plasmodium falciparum’ in the body. RTS, S and several other candidate vaccines teach the immune system to attack the parasite In this sporozoite stage, before invading the liver.
Once the parasite has matured and is released from the liver into the bloodstream, ‘Plasmodium falciparum’ RH5 is expressed and infects red blood cells, causing disease. If a combined anti-sporozoite and anti-Rh5 vaccine were to be used in the future, individuals could experience more effective protection against malaria over a longer period of time.
“The data from the Phase 1b trial reported here confirm for the first time that adequate anti-Rh5 immune responses can be safely achieved.” vaccination in babies from an area where malaria is endemic,” the authors say.
The researchers tested the vaccine in Bagamoyo, Tanzania, where the average prevalence of malaria in the entire population is 13%. they signed up 63 participants range in age from 6 months to 35 yearsThose were randomly assigned to receive an experimental malaria vaccine called ‘ChAd63-MVA RH5’, or a control rabies vaccine.
The trial was also double-blind, meaning Neither participants nor vaccine administrators knew who was getting the malaria vaccine or control. All participants were given a second dose of the vaccine two months later and were followed for another four months.
The main objective of this study was To evaluate the safety of this vaccine in populations where malaria is endemic, Participants in both the control and treatment groups reported pain at the injection site and mild fever shortly after vaccination, but the vaccine was generally well tolerated and there were no safety concerns.
A secondary outcome of the study was whether the vaccine would boost an immune response. The researchers found that participants who had received the malaria vaccine Developed antibodies against RH5 in their blood during follow-up.
in the laboratory, These antibodies were able to stop the growth of the malaria parasite At higher levels those are associated with protection against disease.
“These data justify the move to Phase IIb field efficacy trials to determine whether some Level of inhibition of parasite growth This magnitude could eventually protect against clinical malaria,” he says.
The authors state that they observed strong immune response In infants younger than 11 months, then in children 1 to 6 years of age, and then in adults.
“It is still to be understood why the ChAd63-MVA RH5 vaccine produces such high levels of antibodies in infants and young children,” he explains. , Current efforts focus on infants and young children,
Researchers say this is a small study Follow-up of participants for only four months After receiving the complete immunization schedule. They recommend that additional Phase Ia/Ib trials be conducted to optimize the recommended age range, booster schedule and delivery platform of anti-Rh5 vaccines.
Currently it is planned to execute Phase 1b trial in The Gambia In which the effects of a combination of anti-Rh5 and anti-Rh5 vaccines will be studied.