Understanding Mosquirix, the New Malaria Vaccine

In October 2021, the World Health Organization (WHO) made a groundbreaking announcement about the availability of a malaria vaccine. The WHO now recommends that a vaccine called Mosquirix (RTS,S/AS01) be given to certain children that live in areas where malaria is prevalent. 

Malaria is a common sickness. In 2019 alone, almost 230 million cases were present around the world. Although death rates, thankfully, have gone down over the past decade, more than 400,000 people, mostly children, still died from malaria in 2019. Given how serious malaria can be, this vaccine is welcome news.

Until now, a preventative vaccine against malaria hasn’t been available. Researchers have known about the cause of malaria since 1880 — for more than 140 years — but a vaccine has been tough to develop. 

Here, we’ll talk about the new malaria vaccine: what it is, how it works, and why it’s important. 

Is Mosquirix (RTS,S/AS01) the only malaria vaccine?

Yes. Mosquirix is the world’s only malaria vaccine. It’s also called RTS,S. It took researchers more than 30 years to make and study this vaccine. 

Malaria is caused by parasites that are spread by mosquitoes. Plasmodium falciparum is one of these parasites, and it causes the most deadly type of malaria. Mosquirix fights this parasite, but it’s not effective against other malaria parasites. 

GlaxoSmithKline (GSK), a British pharmaceutical company, makes Mosquirix. Organizations like the Malaria Vaccine Implementation Programme (MVIP), PATH, and UNICEF were also closely involved in making the vaccine available. 

If you want to learn more about malaria and how it’s treated, click or tap here. The vaccine is discussed more below.  

Who can use Mosquirix?

Mosquirix can be given to children who are at least 5 months old. This vaccine is injected into a muscle, and four doses are needed altogether. It usually takes about a year to receive all four doses. 

Where is it available?

Mosquirix should be used in locations where malaria is common. In this case, “common” refers to areas where Plasmodium falciparum is present in “moderate to high” amounts. This parasite is mostly found in sub-Saharan Africa, but it can also be found in places like Southeast Asia and Oceania. 

Of note, this vaccine isn’t available in the U.S. The FDA hasn’t authorized or approved it. 

Why is Mosquirix so special?

It may seem common to come across new vaccines, so what makes Mosquirix unique? 

In short, Mosquirix is important because malaria is a common illness, and this is the first vaccine that aims to prevent it. Malaria affects more than 200 million people every year. 

But malaria affects certain areas especially hard. According to the WHO, more than 90% of all malaria cases are in sub-Saharan Africa. More than 90% of people that die from malaria also live in this region. The majority of people that pass away from malaria complications are younger than 5 years old. 

It’s also hard to make a vaccine against a parasite: Parasites have complicated genetics, which alone makes it difficult for scientists to make a vaccine. But parasites also spread in the body in a complex way. Since this vaccine was created specifically to treat malaria and was approved by the WHO, public health experts consider Mosquirix to be a breakthrough.  

By comparison, many other vaccines fight viruses and bacteria. Viruses and bacteria are simpler than parasites, so it’s easier to target specific parts of them when making a vaccine. 

Mosquirix’s introduction also comes at a time when Plasmodium falciparum is starting to become resistant to certain anti-malaria treatments. This includes resistance to artemisinin, a medication that’s often a first-choice treatment option. 

How does Mosquirix work?

Mosquirix helps the body make antibodies that recognize malaria parasites. Antibodies are proteins that help our immune cells (called white blood cells) fight germs like parasites. 

When malaria parasites enter the body, they travel through the bloodstream and go to the liver. In the liver, these parasites can get stronger and multiply. After a child is fully vaccinated with four doses, Mosquirix works by stopping the parasites’ growth in the liver.  

How effective is the new malaria vaccine?

Although the vaccine is a breakthrough, it’s thought to provide only partial protection. It’s not fully effective, but data show that it may help prevent severe disease.

The WHO’s recommendation for Mosquirix is backed by data from more than 800,000 children that were given at least one dose of the vaccine. These children are located in Ghana, Kenya, and Malawi and are involved in pilot programs that are testing the vaccine’s effectiveness. 

Current data show that Mosquirix is about 30% effective against severe illness. Also, in a previous clinical trial of about 2,500 children, four doses of Mosquirix were about 24% effective at preventing malaria symptoms.  

These percentages may seem low. But some experts predict that the vaccine will likely save the lives of more than 20,000 children every year.  

As mentioned, Mosquirix works against only one malaria parasite — Plasmodium falciparum. If someone is infected with a different parasite that causes malaria, such as Plasmodium vivax, Mosquirix won’t be effective. 

What side effects are associated with Mosquirix?

Mosquirix’s side effects are fairly similar to other vaccines. The most common side effects are pain and swelling at the injection site and fever. 

Other side effects may include:

• Appetite that’s less than normal

• Tiredness

• Irritability 

• Diarrhea

When will it be available?

The vaccine is already available in three African countries — Ghana, Kenya, and Malawi. This is because the vaccine is being studied there in pilot programs. These pilot programs are scheduled to continue until 2023. 

But now that the vaccine is recommended to be used outside of these three countries, more vaccines will be needed. GSK, the vaccine’s manufacturer, plans to supply at least 15 million doses to other sub-Saharan African countries every year. 

However, a specific timeline hasn’t been established for how to distribute the vaccine more widely across the continent. A few organizations are expected to meet later this year to plan possible distribution strategies.  

Why trust our experts?

Written by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

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