Explained: What is the new malaria vaccine, how it will help fight killer disease

Abantika Ghosh
A total 3,60,000 children in three African countries - Malawi, Ghana, and Kenya - will be covered every year with the malaria vaccine. (Reuters file photo)

The World Health Organisation issued a statement Tuesday welcoming a pilot project in Malawi of administering a malaria vaccine to children below the age of 2 years. A total 3,60,000 children across three African countries - Malawi, Ghana and Kenya - will be covered every year with the vaccine.

The vaccine has taken three decades to come to fruition, and is the first one ever against a disease that kills 4,35,000 people a year, most of them children. India ranks high in the list of countries worst affected by the mosquito-borne disease.

What is it that makes the RTS,S vaccine unique, and why is the public health fraternity excited about it?

What is the RTS,S vaccine?

The vaccine has been developed by GSK - the company is donating about 10 million doses of the product for the pilot. It was created in 1987 by GSK, and was subsequently developed with support from the Bill and Melinda Gates Foundation. In 2014, the vaccine cleared phase III clinical trials which certified that it was both effective and safe for use in humans. According to a description from PATH's Malaria Vaccine Initiative (MVI), "RTS,S aims to trigger the immune system to defend against the first stages of malaria when the Plasmodium falciparum parasite enters the human host's bloodstream through a mosquito bite and infects liver cells. The vaccine is designed to prevent the parasite from infecting the liver, where it can mature, multiply, re-enter the bloodstream, and infect red blood cells, which can lead to disease symptoms".

PATH is an international nonprofit team of innovators which advises and partners with public institutions, businesses, grassroots groups, and investors to tackle the world's toughest global health problems, including malaria. MVI works with various stakeholders towards the development of a malaria vaccine.

In Phase 3 trials conducted in Africa between 2009 and 2014, children received four doses of RTS,S. The vaccine prevented four in 10 cases of clinical malaria; three in 10 cases of severe malaria; and six in 10 cases of severe malaria anaemia, the most common reason children die from malaria. There were reductions in overall hospital admissions and the need for blood transfusions.

"We have seen tremendous gains from bed nets and other measures to control malaria in the last 15 years, but progress has stalled and even reversed in some areas. We need new solutions to get the malaria response back on track, and this vaccine gives us a promising tool to get there. The malaria vaccine has the potential to save tens of thousands of children's lives," WHO Director-General Dr Tedros Adhanom Ghebreyesus said.

Why is malaria such a major global public health challenge?

Malaria is a potentially life-threatening parasitic disease caused by the parasites Plasmodium viviax (P.vivax), Plasmodium falciparum (P.falciparum), Plasmodium malariae (P.malariae), and Plasmodium ovale (P.ovale), transmitted by the female Anopheles mosquito.

Malaria, according to the WHO, remains one of the world's leading killers, claiming the life of one child every two minutes. Most of these deaths are in Africa, where more than 2,50,000 children die from the disease every year. Children under the age of 5 are at greatest risk from its life-threatening complications.

"Malaria is a constant threat in the African communities where this vaccine will be given. The poorest children suffer the most and are at highest risk of death. We know the power of vaccines to prevent killer diseases and reach children, including those who may not have immediate access to the doctors, nurses and health facilities they need to save them when severe illness comes," Dr Matshidiso Moeti, WHO Regional Director for Africa, said.

How badly is India affected by malaria?

India ranks very high in the list of countries with a serious malaria burden. In 2018, 3,99,134 cases of malaria and 85 deaths due to the disease were reported in the country, according to data from the National Vector Borne Disease Control Programme.

Questions are repeatedly asked about the veracity of the Indian data, with some reports suggesting India may be recording just 8% of the actual number of malaria cases. Between 60% and 80% of patients in the urban areas are treated by private doctors or health establishments, most of whom do not notify cases. Although malaria is a notifiable disease, it is only voluntary notification - there are no penalties for doctors or hospitals not doing so. However, there is, of late, renewed focus on case reporting.

Six states - Odisha (40%), Chhattisgarh (20%), Jharkhand (20%), Meghalaya, Arunachal Pradesh, and Mizoram (5-7%) - bear the brunt of malaria in India. These states, along with the tribal areas of Maharashtra and Madhya Pradesh, account for 90% of India's malaria burden.

What is the next step for the malaria vaccine now?

The pilot countries - Malawi is the only one that has actually started it; Kenya and Ghana will follow - were chosen after they responded to a WHO call for expressions of interest. Ten African countries were in the fray and these three countries were selected for their well-functioning malaria and immunization programmes, and for their areas with moderate to high malaria transmission. In the selected areas in the three countries, the vaccine will be given in four doses: three doses between 5 and 9 months of age, and the fourth dose around the child's second birthday.

"This novel tool is the result of GSK employees collaborating with their partners, applying the latest in vaccine science to contribute to the fight against malaria. We look forward to seeing the results of the pilot, and in parallel, are working with WHO and PATH to secure the vaccine's sustained global health impact in the future," Dr Thomas Breuer, Chief Medical Officer of GSK Vaccines, said.

Once the pilots have been completed, the WHO will review the results and come out with its recommendations for the use of the vaccine. For a country like India, the key question though is likely to be as much the efficacy of the vaccine as its cost.