The first malaria vaccine, Mosquirix, was approved by the WHO in 2021. Studies show that a real milestone has been reached.
Developing an effective vaccine against malaria has proven to be much more difficult than developing an anti-COVID-19 vaccine. Several different vaccines against COVID-19 have been developed and approved for use within one year of disease onset.
On the other hand, it took more than 30 years of intensive research and numerous clinical trials conducted by the Walter Reed Army Institute of Research and its partners for the first vaccine against malaria, Mosquirix, to be approved by the World Health Organization (WHO) in 2021.
Implementing a vaccine against a vector-borne disease such as malaria is a real challenge. The parasite takes different forms in different hosts. And it is constantly evolving to evade the human immune system and control interventions.
An important step towards the equitable deployment of Mosquirix was taken with the decision of the WHO granting the status of prequalification of the vaccine in September 2022. The prequalification stage follows approval. It ensures that only good quality products are purchased and distributed by UN agencies and other major donors.
More recently, researchers from Burkina Faso and the University of Oxford's Jenner Institute – the same institution that developed the Oxford/AstraZeneca COVID-19 vaccine – made their own revelation. They published very encouraging results from a clinical trial evaluating the new R21 malaria vaccine.
Like Mosquirix, the R21 vaccine targets the sporozoite. This is the stage of the malaria parasite that is transferred to humans when the female malaria-infected Anopheles mosquito sucks blood. When effective, both vaccines ensure that the sporozoites are destroyed before entering the liver. They effectively prevent malaria infection by stopping the life cycle of the parasite in the human host.
The fight against malaria has been considerably strengthened by the addition of antimalarial vaccines to the package of prevention measures. These vaccines have the potential to reduce malaria-related illness and death in children under five – one of the layers currently most affected by malaria.
What studies show
Both vaccines – Mosquirix and R21 – target the same parasite stage and use the same malaria proteins. But Oxford's R21 vaccine contains more of these malaria proteins. It also uses a different adjuvant – a chemical that boosts the body's immune response. These two factors are thought to improve the effectiveness of the R21 vaccine by eliciting a stronger immune response.
Preliminary data is taken froma study two-year study involving 409 children aged five to 17 months. Children received a booster dose 12 months after receiving the first three doses of the vaccine. The data suggest that the R21 vaccine resulted in a protection level higher than the Mosquirix.
Eight out of ten children who received four doses of the R21 vaccine did not develop malaria during the trial period – making this malaria vaccine the first to reach the target ofminimum efficiency of 75% for 12 months in the target population of young African children.
The results of this study are encouraging. But the researchers cautioned against a direct comparison between the performance of the R21 and Mosquirix vaccines. Unlike the Mosquirix vaccine, the R21 vaccine was given to children before the start of the malaria season. And there was no tested only on a small number of children in one region of Burkina Faso. In addition, a number of control and prevention measures were in place.
A larger study is needed to confirm the efficacy of the vaccine in African children across the continent. This study should be conducted in areas where the intensity of malaria transmission, levels of malnutrition and anemia in target populations, and coverage of control interventions vary.
Four thousand eight hundred children from four African countries – two of which have year-round malaria transmission – have been enrolled in a Phase 3 clinical trial. The aim of this trial is to demonstrate the safety and efficacy of the vaccine in a larger and more diverse group of children. Jenner Institute researchers expect the R21 vaccine to be approved for use next year, provided no unexpected safety issues arise in this larger trial.
Personalized bottlenecks in manufacturing and distribution have impeded the timely and equitable distribution of COVID-19 vaccines. To prevent this from happening again, the University of Oxford has signed a manufacturing agreement with the Serum Institute of India, the world's largest vaccine manufacturer. Under this agreement, the Serum Institute has agreed to provide at least 200 million doses per year. This is far more than the 15 to 18 million doses of Mosquirix that GlaxoSmithKline must produce each year. up to 2028.
But, according to the WHO, this amount is much lower than Requirement planned vaccines. To increase production capacity, the Jenner Institute is in talks with African vaccine manufacturers.
The next steps
Making vaccines is only the first step. It is also necessary to ensure that countries can obtain the vaccines, that they are delivered equitably to the requesting countries and that the vaccines are distributed quickly to all health facilities in areas at risk of malaria. And above all, the use of vaccines must be optimal.
La misinformation, vaccine hesitancy, and safety concerns have contributed to lower COVID-19 vaccination rates, especially among children.
For a malaria vaccine to have an impact, health promotion is essential. Awareness campaigns should address safety issues, while emphasizing the expected positive effects of the vaccine.
These campaigns should target both health professionals and affected communities. They should be conducted before and during vaccine deployment to ensure that any new misinformation or concerns are addressed quickly and effectively.
Jaishree Raman, Principal Medical Scientist and Head of Laboratory for Antimalarial Resistance Monitoring and Malaria Operational Research, National Institute for Communicable Diseases
This article is republished from The Conversation under Creative Commons license. Read theoriginal article.