The groundbreaking malaria vaccine for children at risk

October 6, 2021 has been a historic day: WHO gave the final green light to the use of the first vaccine against malaria, one of the deadliest infectious diseases, which causes over 400,000 deaths every year, especially in sub-Saharan Africa. To give an idea of ​​the emergency: a child dies from malaria every two minutes.

The approved vaccine is called RTS,S/AS01 (Mosquirix, produced by GlaxoSmithkline), and WHO has recommended its administration in children under the age of 5 living in areas of moderate to high malaria transmission.

“This is a historic moment. The long-awaited malaria vaccine for children is a breakthrough for science, child health and malaria control” said WHO Director-General Dr Tedros Adhanom Ghebreyesus. “Using this vaccine on top of existing  tools to prevent malaria could save tens of thousands of young lives each year”.

We talked about this exceptional result with Prof. Antonella Castagna, Associate of Infectious Diseases and Director of the UniSR Postgraduate Course in Infectious and Tropical Diseases, as well as head of the Infectious Diseases Unit of the San Raffaele Hospital.

Anopheles mosquitoes, vectors of malaria

Malaria is caused by protozoa [parasitic organisms] of the Plasmodium genus and transmitted through the bite of a vector insect, the female mosquito of the Anopheles genus, which generally bites humans from dusk to dawn. It is a preventable and treatable disease, yet still today Plasmodium falciparum malaria [one of the most dangerous species of plasmodium that causes malaria in humans], represents an urgency, sometimes a medical emergency, with mortality rates still too much elevated.

In 2019, 229 million cases were estimated worldwide, of which over 90% in sub-Saharan Africa and over 400,000 deaths, 274,000 of which in children under the age of 5.

Symptoms, diagnosis and treatments of malaria

Generally, the symptoms appear one week after the infectious sting and there are no clinical features that allow it to be differentiated from other infectious diseases. Therefore, every febrile episode in those who have stayed in the previous 3-4 months in endemic areas, implies that malaria is the first pathology to be excluded.

Diagnosis is simple and timely and early diagnosis is the key element in reducing the risk of severe and complicated malaria and mortality. We have effective drugs for the treatment of P. falciparum malaria, although there are some strains of plasmodia resistant to drugs such as chloroquine (a phenomenon widespread in almost all of sub-Saharan Africa, a large part of South-East Asia and a large part of Amazonia) and mefloquine (in some areas of the Indochinese peninsula and in some areas of Sub-Saharan Africa). Doctors also have established combination therapeutic schemes even in the hospital treatment of the most severe forms.

ABCDE principles to prevent malaria

Come citato in precedenza, la malaria è una malattia prevenibile. L’OMS ha sintetizzato i comportamenti cardine per proteggersi efficacemente dall’infezione, stilando i cosiddetti :

As mentioned earlier, malaria is a preventable disease. WHO has summarized the key behaviors to effectively protect from infection, drawing up the so-called ABCDE principles:

1. risk awareness;
2. avoid being bitten;
3. chemoprophylaxis (taking preventive drugs against the development or spread of a disease);
4. diagnosis;
5. presumptive emergency treatment (immediate intervention in case of suspicious symptoms).

The Mosquirix vaccine and the new studies

In this scenario, 6 October 2021 has been a historic day: WHO gave the final green light to the use of Mosquirix vaccine in children under the age of 5 living in areas of moderate to high endemic risk. It is a recombinant vaccine composed of Plasmodium falciparum circumsporozoite protein and combined with hepatitis B surface antigens, administered intramuscularly in three doses at one month intervals, with a booster 18 months after the last administration.

WHO's decision is based on the results of the pilot program initiated in three countries in Sub-Saharan Africa, Ghana, Kenya and Malawi, which involved over 800,000 children: the RTS,S vaccine is safe, and although it does not provide complete protection, it reduces the risk of malaria by 39% and the risk of complicated malaria by 29%.

Also very encouraging are the results of the study published a few weeks ago in the New England Journal of Medicine, conducted in the Sahel (in sub-Saharan Africa) starting from 2016 in over 6800 children aged between 5 and 17 months. The use of the vaccine combined with the use of chemoprophylaxis and mosquito nets has led to a reduction of over 60% in the risk of hospitalization and death from malaria. The vaccine could prevent millions of cases and many thousands of deaths in children every year - a decisive step in the long fight against this disease.