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EXPLAINED: More Than 30 Yrs In The Making, How Malaria Vaccine Finally Got WHO's Nod

The vaccine developed by GSK has a four-dose regimen starting at when the child is 5 months old

The vaccine developed by GSK has a four-dose regimen starting at when the child is 5 months old

The WHO Chief has hailed it as an "historic moment" in the fight against malaria. Here's a look at the first vaccine to get the nod against the disease

At a time when the world is contending with a hitherto unseen and unknown foe in the novel coronavirus, you might wonder why a vaccine for malaria is making news. The Covid-19 pandemic may have had an unprecedented impact on societies, health systems and economies, but the fact remains that malaria has long continued to extract a heavy toll in mostly developing countries across the world, especially in sub-Saharan Africa, without there being any fully authorised protective shield to provide immunity against it. Until now, that is. Here’s what you need to know about the world’s first anti-malaria vaccine.

What Is The Vaccine?

The RTS,S/AS01 vaccine, which has the brand name Mosquirix, has been developed by the UK-based pharma major GSK to act against Plasmodium falciparum, “the deadliest malaria parasite globally and the most prevalent in Africa". The World Health Organisation (WHO) says that the vaccine “significantly reduces malaria and life-threatening severe malaria in children".

While the WHO recommendation for its widespread use among children living in regions with moderate to high transmission of the P. falciparum malaria has only come in October 2021, the vaccine itself had been under development for more than 30 years with its makers submitting Phase-III trial reports in 2015, following which WHO launched a pilot in the three sub-Saharan African countries of Ghana, Malawi and Kenya. This pilot has covered more than 800 000 children since 2019 and its findings have led to the nod for the vaccine’s wider rollout.

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The global health body said that RTS,S is “the first malaria vaccine that has completed the clinical development process", pointing also to the thumbs up the vaccine has received from the “stringent" European Medicines Agency.

How Bad Is The Malaria Problem Worldwide, And In India?

Caused by parasites that are spread among humans through the bites of infected female Anopheles mosquitoes, malaria is a life-threatening, yet preventable and curable, disease that accounted for close to 23 crore infections and about 4 lakh deaths in 2019.

WHO says that Africa “carries a disproportionately high share of the global malaria burden", reporting 94 per cent of all malaria cases and deaths worldwide in 2019. The disease especially affects children and those under 5 years are the most vulnerable group, making up 67 per cent, or 2.74 lakh, of all malaria deaths worldwide in 2019.

Malaria is endemic to India, too, but the country has reported a significant drop in numbers in recent years. Citing the WHO World Malaria Report 2020, the Union health ministry had said in December last year that “India has… contributed to the largest drop in cases region-wide, from approximately 20 million to about 6 million". It added that malaria cases dropped by 71.8 per cent while deaths declined by 73.9 per cent between 2000 to 2019.

How Does It Work?

The RTS,S vaccine is a recombinant protein-based vaccine, which means that, to spur the immune system to produce antibodies against the disease, it relies on inserting specific pieces of the pathogen that have been purified rather than the whole pathogen. These specific pieces are specially selected for their ability to stimulate immune cells and, since these fragments are incapable of causing disease, subunit vaccines are considered to be quite safe.

RTS,S is a four-dose vaccine with WHO recommending that the first dose be administered at 5 months old. Two follow-up doses are to be given in the sixt and seventh months while a final booster is administered at around 18 months.

WHO said that two years of data from the three-country pilot shows that “more than two-thirds of children… who are not sleeping under a bednet are benefiting from the RTS,S vaccine". The vaccine has also achieved a 30 per cent reduction in deadly severe malaria among children even in those areas where other preventive measures, like mosquito or bed nets, are widely used and good treatment facilities are available.

Why Did It Take So Long To Develop A Malaria Vaccine?

Dr Pedro Alonso, the director of the WHO Global Malaria Programme, said in reference to its rollout that health experts have “been looking for a malaria vaccine for over 100 years now". GSK, the maker of the vaccine, said it was under development for more than 30 years although it was proven effective six years ago and the latest decision relates only to its launch for the general public.

One key reason why a malaria vaccine has been difficult to develop is the nature of the parasite itself. According to the US diseases watchdog, the several obstacles that hit the development of a malaria vaccine include “the lack of a traditional market, few developers, and the technical complexity of developing any vaccine against a parasite".

It notes that malaria parasites have a complex life cycle, and “there is poor understanding of the complex immune response to malaria infection". It said that exposure to the “genetically complex" malaria parasites — of which there are more than 100 types — does not confer lifelong protection.

While the RTS,S vaccine targets only the Plasmodium falciparum variety, the most deadly and common one in Africa, there are other varieties like Plasmodium vivax which, along with P. falciparum, is among the more widespread varieties in India. WHO says that the vaccine will not work against the other varieties of the parasite.

According to the Union health ministry, five states — Odisha, Chhattisgarh, Jharkhand, Meghalaya, Madhya Pradesh — “disproportionately accounted for nearly 45.47 per cent of malaria cases and 70.54 per cent of falciparum malaria cases in 2019".

The complexity of the parasite is also one reason why vaccine makers have struggled to achieve a high efficacy rate against it. RTS,S has an efficay rate of about 40 per cent, that is, it has been found to prevent 4 out of 10 cases of malaria caused by P. falciparum. Which could explain why the WHO has said that the vaccine should be used as a force multiplier that complements, and does not replace, other measures to combat malaria such like the use of mosquito nets, insecticides, etc.

How Soon Will The Vaccine Be Available?

GSK has said that it will donate up to 10 million RTS,S doses for use in the pilots and supply up to 15 million doses annually. India will be key to the production of the vaccine as the company has entered into a “technology transfer for long-term antigen production" with Bharat Biotech, the maker of the Covaxin, one of the frontline shots against Covid-19 in India.

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first published:October 07, 2021, 11:41 IST