A Vaccine for Malaria: An Unattainable Goal or a Realistic Future?
By Asmithaa Vinukonda, Forsyth Country Day School, Winston-Salem, North Carolina, USA
Since the discovery of the first malaria parasite in 1880, scientists have been looking to develop a combative vaccine. Although some vaccines have been successful with certain viral and bacterial pathogens, the deadliest species of malaria, Plasmodium falciparum (P. falciparum), has not yet been bested (Frimpong et al., 2018). However, many vaccine candidates are currently being tested and could possibly pave the way for malaria eradication in the future.
Malaria is a formidable enemy for scientists to target. The world sees around 300 million cases each year with at least half a million of these resulting in death (Wellcome Sanger Institute, n.d.). Not only is the parasite prevalent and deadly, but it also evades antibiotic treatment.
Antibiotic resistance has only worsened the situation. Over the past 50 years, P. falciparum had developed resistance to all antimalarial drugs, including chloroquine, sulphadoxine-pyrimethamine, quinine, piperaquine, and mefloquine. More recently, P. falciparum has also developed resistance to artemisinin-based combination therapies that previously aided in controlling it (Thu, 2017). With no effective and permanent treatment remaining, the only way to possibly eradicate malaria is through a vaccine.
Of course, there are challenges when developing a malaria vaccine as well. The disease is widespread in developing tropical and subtropical countries of the world. Due to lack of economic infrastructure in these regions, charitable organizations such as the Bill and Melinda Gate Foundation and the EU Malaria Fund are often the only institutions spearheading vaccine development efforts. Finances are only part of the problem - the parasite itself presents a scientific conundrum. P. falciparum is a parasite, not a virus, with a complex life cycle in two hosts: humans and female Anopheles mosquitos. There is little understanding of the human immune system’s response to malaria infection because of its parasitical nature. Additionally, malaria infection does not guarantee future immunity. Any acquired immunity does not fully protect against future disease either (Centers for Disease Control and Prevention, n.d.). Therefore, only two vaccines have gained any traction as of now.
The PfSPZ vaccine is one of the vaccines that shows promise. It includes whole sporozoites, the sexual form of the parasite, that have been made non-infectious. Created by Sanaria Inc., the vaccine has been shown to be safe and has promising protection against malaria, particularly in infants and young children. Other studies are currently evaluating the efficacy of the vaccine in different populations from various locations (Centers for Disease Control and Prevention, n.d.).
The RTS,S/AS01 vaccine is the second vaccine with some efficacy particularly in pediatric patients, and it is the first malaria vaccine to make it to Phase Ⅲ clinical testing. Created by GlaxoSmithKline, the vaccine appears to reduce clinical and severe cases of malaria by one-third in infants. The children in the study received the vaccine over four years, including a three-dose series and a booster dose. It was generally found to be safe, but there were a few safety signals that warranted further study. It is important to note that this vaccine provided protection in settings where there is ongoing use of other effective malaria prevention and treatment interventions (Center for Disease Control and Prevention, n.d.). This means that the same success may not be replicated in areas where these treatment interventions are not implemented. Additionally, the vaccine does not guarantee lifelong protection, benefits only four in ten children from five to seventeen months, and is less cost-efficient than mosquito nets (Adepoju, 2019).
Of course, after an effective vaccine is developed, there will be many additional problems to face. Distributing vaccines to poor countries with limited access to resources and transportation will be the first bridge to cross, although many others will follow. But those are hurdles to jump after the world’s health organizations’ goal is met: creation of a 75% effective malaria vaccine that effectively reduces transmission by 2030 (Center for Disease Control and Prevention, n.d.). Whether or not we will get there, only time will tell.
Adepoju, P. (2019, April 27). The new malaria vaccine program for African children is promising but still quite limited. Quartz Africa. https://qz.com/africa/1606511/malaria-vaccine-by-gsk-for-african-children-is-still-too-limited/
Centers for Disease Control and Prevention. (n.d.). Vaccines. Retrieved November 29, 2020, from https://www.cdc.gov/malaria/malaria_worldwide/reduction/vaccine.html
Frimpong, A., Kusi, K. A., Ofori, M. F., & Ndifon, W. (2018). Novel Strategies for Malaria Vaccine Design. Frontiers in immunology, 9, 2769. https://doi.org/10.3389/fimmu.2018.02769
Wellcome Sanger Institute. (n.d.). Plasmodium falciparum. Retrieved November 29, 2020, from https://www.sanger.ac.uk/resources/downloads/protozoa/plasmodium-falciparum.html
Thu, A. M., Phyo, A. P., Landier, J., Parker, D. M., & Nosten, F. H. (2017). Combating multidrug-resistant Plasmodium falciparum malaria. The FEBS journal, 284(16), 2569–2578. https://doi.org/10.1111/febs.14127