Are We Finally Winning Against the Mosquito?

It’s been a long time in the making, but the World Health Organization (WHO) has announced that three countries, Ghana, Kenya, and Malawi, have been selected to begin trials of a new malaria vaccine next year. At least 120,000 children in each country, ranging from five to 17 months old, will receive the vaccine, which must be delivered in four doses.

Malaria infects more than 200 million people every year and kills more than 400,000. A large percentage of those are children. These three countries were chosen not only because they are hot spots for malaria, but also because they already have strong vaccination programs in place for other types of vaccines. The malaria vaccinations will take place through those existing programs.

Given how prevalent malaria has been for centuries, it’s amazing that it’s been so difficult to get to this point. We’ve reduced populations of the mosquitoes that transmit the disease, both through the use of insecticides and through measures such as eliminating areas of standing water. We’ve even been able to genetically modify mosquitoes to prevent them from successfully breeding.

But for all the progress some countries like Brazil once made in reducing mosquito populations—largely through the use of DDT—they can come back with a vengeance when the pesticides are reduced or stopped. The vaccine isn’t a perfect solution either; it has an efficacy of only 26 to 50%. But in an earlier phase of the trials, 11,000 children in sub-Saharan Africa received the vaccine, and it reduced mortality by almost 50%.

We’re fortunate in the northern hemisphere to have fewer of the mosquitoes that spread diseases like malaria and dengue fever. We do, however, have those that carry the West Nile virus (for which a vaccine is under development), the Zika virus, and others for which no vaccines yet exist. Eliminating the mosquitoes’ breeding grounds is still important in controlling the diseases, and maintenance of stormwater structures—as we’ve covered here and here, for example—is a big part of that.

The vaccine currently undergoing trials, known as RTS,S or by the trade name Mosquirix, was developed by GlaxoSmithKline. It targets one of the four varieties of malaria that affects humans, Plasmodium falciparum, which is the most deadly. Other potential vaccines are also under development. The World Health Organization has a goal of eliminating malaria by 2040.