Last updated on September 8th, 2022 at 12:40 pm
Although it may seem like all we talk about are the COVID-19 vaccines, but there’s more going on out there. One is a new breakthrough malaria vaccine that may bring an end to this scourge.
We are still a few years away from this vaccine being widely available, but since control of malaria has been a goal of scientists for a long time, a potential malaria vaccine is something that should be celebrated widely.
What is malaria?
Malaria is caused by a single-celled parasite from one of four related microorganisms in the Plasmodium group. It is carried to humans by an infected female Anopheles mosquito.
Malaria is endemic to tropical areas across the world, including Sub-Saharan Africa, South America, and Asia. However, it used to be prevalent in other areas, such as Southern Europe and Southern USA, until post World War II eradication efforts, including the use of the environmentally dangerous DDT, eliminated it in those areas. Of course, with climate change, the mosquito vector may spread far beyond its current areas.
Malaria infection develops via two phases – one that involves the liver (exoerythrocytic phase), and one that involves red blood cells, or erythrocytes (erythrocytic phase). When an infected mosquito pierces a person’s skin to take a blood meal, malaria sporozoites in the mosquito’s saliva enter the bloodstream and migrate to the liver where they infect hepatocytes, multiplying asexually and asymptomatically for a period of 8–30 days.
After a potential dormant period in the liver, these organisms differentiate to yield thousands of merozoites, which, following rupture of their host cells, escape into the blood and infect red blood cells to begin the erythrocytic stage of the life cycle. The parasite escapes from the liver undetected by wrapping itself in the cell membrane of the infected host liver cell.
Within the red blood cells, the parasites multiply further, again asexually, periodically breaking out of their host cells to invade fresh red blood cells. Several such amplification cycles occur. Thus, classical descriptions of waves of fever arise from simultaneous waves of merozoites escaping and infecting red blood cells.
Malaria symptoms include chills, flu-like symptoms, fever, vomiting, diarrhea, and jaundice. It can be life-threatening if untreated.
Speaking of treatments, malaria is treated with antimalarial medications – the one used depends on the type and severity of the disease.
One of the best methods to prevent malaria is to destroy the mosquito vector, but that brings with it a number of environmental issues. There has been work on a genetically modified mosquito that basically ends the parasite/mosquito life cycle, but we are a long way from that being widely implemented.
There is a malaria vaccine, GlaxoSmithKline Vaccine’s RTS,S/AS01 (RTS,S), that has been approved by the European Medicines Agency. Unfortunately, it has only moderate effectiveness, ranging from 26-50% in children.
However, a new vaccine developed by Oxford (the same Oxford that developed the COVID-19 vaccine distributed by AstraZeneca, but is partnering with Novavax for the malaria vaccine), known as R21, showed up to 77% effectiveness in a Phase IIb clinical trial of 450 children in Burkina Faso over 12 months.
The researchers also noted that there were “no serious adverse events related to the vaccine.”
The researchers are now recruiting 4800 children, aged 5-36 months, for a phase III clinical trial to assess large-scale safety and effectiveness across four African countries.
Novavax and other pharmaceutical partners are hoping to produce 200 million doses annually which would have a “major public health impact if licensure is achieved.” Given the hundreds of thousands of deaths from malaria among children across the world, this vaccine could be a gamechanger.
Vaccines save lives.
- Bledsoe GH. Malaria primer for clinicians in the United States. South Med J. 2005 Dec;98(12):1197-204; quiz 1205, 1230. doi: 10.1097/01.smj.0000189904.50838.eb. PMID: 16440920.
- Vaughan AM, Aly AS, Kappe SH. Malaria parasite pre-erythrocytic stage infection: gliding and hiding. Cell Host Microbe. 2008 Sep 11;4(3):209-18. doi: 10.1016/j.chom.2008.08.010. PMID: 18779047; PMCID: PMC2610487.