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This path-breaking vaccine may win a Nobel, and it's for not Covid

By Devangshu Datta
October 20, 2021 09:00 IST
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The new malaria vaccine (RTS.S/ AS01, tentatively brand-named Mosquirix) is the very first one to offer immunity against a parasite -- specifically the plasmodium falciparum parasite, which is the deadliest of the five parasites that cause malaria.

IMAGE: Kindly note that this image has been posted for representational purposes only. Photograph: ANI Photo

The new malaria vaccine (RTS.S/ AS01, tentatively brand-named Mosquirix) could be a frontrunner for an early Nobel Prize in medicine. It is a game changer for public health and infant mortality. Here's why.

What is so special about it?

It's the very first vaccine offering immunity against a parasite -- specifically the plasmodium falciparum parasite, which is the deadliest of the five parasites that cause malaria.

 

Creating a vaccine to protect against a bacteria or a virus is hard enough. But parasites are more complicated organisms. Cultivating them, understanding how natural antigens build up against them and the differences in the way they affect different animals add to the difficulty of studying them and creating vaccine candidates.

This vaccine uses genes from the outer protein of falciparum, spliced to a portion of a hepatitis B virus, plus some chemicals to induce and boost immune responses and block the parasite.

How long did it take to develop this vaccine and who was involved?

This vaccine has been in development for 30 long years. The bulk of the R&D was by the UK-based multinational GlaxoSmithKline in partnership with a global non-profit, PATH.

There was also vital support from a large network of African research centres spread across several countries. The Bill & Melinda Gates Foundation provided funding between 2001 and 2015.

Funding for the pilots came from three bodies: Gavi, the Vaccine Alliance; the Global Fund to Fight AIDS, Tuberculosis and Malaria; and Unitaid.

The Malaria Vaccine Implementation Programme is now being coordinated by the World Health Organisation. It's supported by governments in Kenya, Malawi and Ghana and multiple agencies like PATH and Unicef. GSK has committed to donating up to 10 million doses.

What does the vaccine do and who does it target?

The vaccine is given in four doses to children starting at five months, with the final dose ideally administered at 18 months. It's "moderately effective" -- remember that it offers protection only against one of the five malaria parasites. Researchers estimate it will cut caseloads by at least 30 per cent, and reduce fatalities by much more than that.

So why is it a big deal if it "only" cuts caseloads by 30 per cent?

Around 400,000 people die from malaria every year. The vast majority die from falciparum infections, which attack the liver, among other things.

Two-thirds of fatal cases -- about 275,000 -- involve children. Around 94 per cent of those cases are in sub-Saharan Africa. Somewhere on earth, a child dies every two minutes from malaria. Moreover, even kids who don't die get repeated bouts, leading to other health problems.

Malaria imposes costs of $12 billion every year in Africa alone (these are poor countries) in terms of lost man-days, healthcare, etc.

Even in India, which has done better in terms of managing an endemic disease, there were 6 million cases and 7,700 deaths in 2019 -- and mostly it was children who died, again mostly of falciparum.

How safe is it especially since it's to be administered to infants?

Over 800,000 children have already been vaccinated in pilot programmes in Kenya, Malawi and Ghana, starting 2019 and continuing through the pandemic. That's over 2.3 million doses so far. It's safe and certified as such by the European Medicines Agency apart from the WHO. The pilots showed more than two-thirds of children in the three countries, who were not sleeping under an insecticide-treated bednet, benefited from the vaccine.

Does the vaccine offer immunity for life?

Sadly, no. And we don't really have details about the timing and numbers of booster doses yet. But several other malaria vaccines are also in various stages of development. For example, the R21/Matrix-M has shown 77 per cent efficacy in initial trials, which is better than Mosquirix. This is being developed through a collaboration between Oxford University, the Kenya Medical Research Institute, the London School of Hygiene & Tropical Medicine, Novavax, the Serum Institute of India, and the Institut de Recherche en Sciences de la Santé, Burkina Faso.

What else is being done to combat malaria?

There are several other vaccine candidates and there's R&D targeting the other parasites. Apart from that, insecticide-treated bed-nets help reduce infections.

There are audacious experiments involving releasing hundreds of millions of genetically modified Aedes aegypti mosquitoes into Florida, after pilot trials in Brazil. These genetically modified mosquitoes are male (only female mosquitoes bite, and only when carrying eggs). Any females they mate with will only give birth to male mosquitos -- their female eggs will die.

In a few generations, this could lead to a drastic reduction of the Aedes aegypti population. That would be a good thing since Aedes carries dengue, Zika, and yellow fever. Similar genetically modified programmes may target the Anopheles mosquito, which carries malaria. There are large environmental risks to such programmes, however. The mosquito is a key link in the food chain for frogs, turtles, lizards, etc.

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Devangshu Datta
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