Since the vaccine was announced, a number of contradictory reports and comments have been circulating on the internet, and you’re probably wondering which ones to consider. To help you dispel your doubts, we’re going to refer to the 5th point of our previous article on how to assess the reliability of medical information, namely “Understanding the science behind the information you receive”.
NB: This article is not intended to convince you to accept this vaccine (I have no conflict of interest). In line with the vision of this blog expressed by its slogan (Know – Understand – Act for better health), the aim of this article is to provide you with accurate information so that your decision should be guided by an understanding of what you have heard so far.
1) Malaria: everything you need to know about the disease
It would be difficult to understand the science behind a vaccine against a disease if you don’t have some understanding of the mechanisms of the disease itself. So I invite you to read this article first, which will give you a good understanding of malaria. In that article, we explained the science behind this disease, how the microbe enters our body through a particular mosquito bite, and how it causes serious damages that manifests as the symptoms or signs of the disease. We finished with the means of prevention, and as promised, now comes the long-awaited article on the Mosquirix vaccine, newly introduced in Cameroon on 22 January 2024.
2) What must be known about vaccines
Before explaining how the malaria vaccine works, it would be helpful for you to have a clear basic understanding of vaccines in general. You can read our articles explaining: what vaccines are, their usefulness, and above all the article explaining how they are developed before being administered to humans.
3) Is this RTS,S/AS01 (Mosquirix) vaccine being tested on Cameroonians?
I could give you a simple “yes” or “no” answer, but that would just be my opinion among many others you’ve seen around.
For example, in a video that became viral in late November 2023 after the arrival of Mosquirix vaccines in Cameroon, the political activist Egountchi BEHANZIN radically advised the people of Cameroon against accepting this vaccine, which he said had been created in 2021. The translation of what he said in that video goes like this: “Before a vaccine can be put on the market, 10 years of tests are needed, but this vaccine was created in 2021 and is still in the experimental phase […] This means that the safety guarantees for this vaccine are not in place today, because it takes 10 years before the vaccine can be put on the market and the vaccine has only been developed since 2021“. These statements are not true, and you can see for yourself by reading (if you have not yet done so) this article which explains how vaccines are developed before being administered to humans. Furthermore, the Mosquirix vaccine began development over 60 years ago and has gone through all the stages of vaccine development; in 2021 it reached the stage of regulatory approval by the WHO (World Health Organisation). The chronology of this vaccine’s development is shown in the image below, taken from an article by Isaac Olufadewa and colleagues, published in the Journal of Global health.
On 22 November 2023, Cameroon received 331,200 doses of the first malaria vaccine recommended by the WHO: RTS,S/AS01, also known as Mosquirix. Two months later, on 22 January 2024, this vaccine was officially included in the immunisation schedule of the Expanded Programme on Immunisation (EPI-Cameroon). This first introduction concerns children aged 06 months, who will receive the recommended 04 doses of vaccine up to the age of 24 months in 42 health districts that have been prioritised by the National Malaria Control Programme and the EPI-Cameroon.
4) RTS,S/AS01 vaccine (Mosquirix): How does it work in the body?
4-1) The main player, also known as “CSP” (Circumsporozoite Protein)
When an infected mosquito bites a person, it introduces malaria microbes (Plasmodium falciparum) into the bloodstream. These microbes then move to the liver and infect the liver cells, where they multiply before invading the red blood cells and causing the symptoms of the disease. CSP is a specific protein found on Plasmodium falciparum (the malaria microbe), and it is this protein that opens the door of the liver cells to Plasmodium falciparum.
During the first stage in the development of the Mosquirix vaccine, it was the CSP that the scientists identified as the antigen (see article on the stages in vaccine development).
4-2) Mosquirix vaccine action in the body and its impact
The RTS,S/AS01 vaccine contains some fragments of this CSP, which stimulates the immune system to produce specific antibodies directed against it. In other words, the vaccine will provoke the production of the military and specific weapons that can neutralise the CSP (prevent the CSP from opening the doors of the liver cells).
When a person is vaccinated, their immune system becomes able to recognise the CSP as a threat. So, if that person is bitten by an infected mosquito, the antibodies produced in response to the vaccine can target and neutralise the malaria microbes that have the CSP, before they invade the liver cells. This vaccine therefore helps to fight against malaria:
- By preventing or reducing the penetration of Plasmodium falciparum into liver cells, which will prevent the microbe from multiplying, preventing the destruction of liver cells and red blood cells, and consequently reducing the risk of complications and the severity of the disease (see article on malaria). It is through this mechanism that the vaccine helps to reduce the risk of severe forms of the disease and death.
- By reducing the quantity of Plasmodium falciparum available in the blood, the mosquito will have less chance of being infected by this microbe when it bites a vaccinated person, and therefore less chance of transmitting the Plasmodium to another person it bites later. This is how the vaccine helps to reduce the transmission and spread of the disease.
5) About the rumours concerning Mosquirix
Dr Hemes Nkwa, Field Epidemiologist Medical Doctor and blogger specialised in fact-checking, has written an informative article to help you separate the “true” from the “false” in 3 points. I strongly recommend that you read this article, which will help to dispel many of your doubts.
Key Takeaways
By understanding how this vaccine works, you can better understand how it can help to reduce the spread or transmission of the disease and reduce the risk of becoming seriously ill with malaria, as is regularly repeated by national and international health authorities.
Our aim by writing this article is not to tell you whether to accept or reject the Mosquirix vaccine, also known as RTS,S/AS01. Our aim is to give you precise and dispassionate information (in a language you can understand), so that you can make your own decision for your children and your community. So whether you choose to have your children vaccinated or not, we hope this article has helped you to better understand the subject, because that’s what we have committed ourselves to.
In our next article on this vaccine, we’ll be tackling a major question: “Is this vaccine essential? Why not simply apply the other malaria control measures we already know better?“
Don’t hesitate to ask your questions and tell us in the comments if this article has enlightened you, and if your perception of the Mosquirix vaccine has changed (or not at all) after reading it. See you soon!
Dr Christelle Mpoulet, Field Epidemiologist Physician and Freelance Writer (production of medical content combining scientific rigour and editorial clarity for an effective and impactful health communication)
