The recent announcement by the World Health Organization (WHO) regarding the endorsement of the R21/Matrix-M malaria vaccine, a co-development effort by the University of Oxford and the Serum Institute of India, has garnered global attention. The spotlight on the Matrix-M component, a unique saponin-based adjuvant brought about by Novavax and licensed to the Serum Institute for usage in endemic nations, has yielded a renewed interest in the fight against malaria. The vaccine is currently being used in Ghana, Nigeria, and Burkina Faso.
Understanding Adjuvants
The term “adjuvant” stands for an ingredient within a vaccine that enhances the immune system’s response to the same. Its role is to boost the immune system’s capacity to recognize and recall the content of the vaccine, thereby extending the duration of the vaccine’s protective properties. Deriving from saponins – natural compounds found within the bark of Chile’s Quillaja saponaria tree – the Matrix-M adjuvant represents a breakthrough in vaccine technology, given saponins’ historical record of medicinal applications.
Malaria: A Brief Overview
Malaria, a life-threatening ailment caused by Plasmodium parasites, is transmitted to humans through the bites of infected female Anopheles mosquitoes. There are five different species of Plasmodium parasites that induce malaria in humans, among which P. falciparum and P. vivax bear the highest risks. While P. falciparum is the deadliest of them all and prevails primarily in the African continent, P. vivax dominates most countries outside Sub-Saharan Africa. Other malaria-causing species are P. malariae, P. ovale and P. knowlesi.
Malaria Symptoms and Prevalence
Mild symptoms of malaria include fever, chills and headaches, while serious cases can manifest as fatigue, confusion, seizures and difficulty in breathing. According to the World Malaria Report 2022 by WHO, there were 247 million cases reported in 2021, compared to 245 million in 2020, with the majority occurring in tropical countries. Nigeria, the Democratic Republic of the Congo, United Republic of Tanzania and Niger top the list of countries accounting for over half of global malaria fatalities.
Malaria Vaccines
The endorsement of R21/Matrix-M vaccine comes alongside the recommendation of RTS,S/AS01 malaria vaccine’s extensive usage among children residing in regions with moderate to high P. falciparum transmission.
Global and National Strategies for Malaria Elimination
The Global Technical Strategy for Malaria 2016–2030, updated in 2021, outlines a set of ambitious yet achievable global targets to combat malaria. The plan includes reducing case incidence and mortality rates by at least 90% by 2030, eliminating malaria in at least 35 countries by 2030, and preventing resurgence in all malaria-free countries.
In India, the National Framework for Malaria Elimination (2016-2030) and Malaria Elimination Research Alliance-India (MERA-India) are key strategies focused on achieving these objectives.
Challenges to Malaria Vaccine Development
Despite advancements, developing an effective malaria vaccine poses significant challenges, primarily owing to the existence of multiple Plasmodium species and the lack of long-lasting immunity against malaria after natural infections. These obstacles have sparked widespread efforts to develop better interventions, including more efficient vaccines.