NOVA: "The Battle to Beat Malaria" (Wingspan Productions, GBH, PBS, 2023)

by Mark Gabrish Conlan • Copyright © 2023 by Mark Gabrish Conlan for Zenger's Newsmagazine • All rights reserved

Last night (Wednesday, November 15) I watched a couple of the science shows PBS regularly airs Wednesday nights, a NOVA show called “The Battle to Beat Malaria” and a Secrets of the Dead episode titled “Hidden in the Amazon.” “The Battle to Beat Malaria” centered around a proposed malaria vaccine called R21/Matrix M developed at Oxford University by a team of scientists including Adrian Hill, who talked about the scientific challenges of designing a malaria vaccine and why the previous candidates hadn’t worked. Malaria is an infectious disease spread by the bites of a female Anopheles mosquito; when a female Anopheles has sex, she literally puts the bite on the nearest warm-blooded animal she can find. She inserts a built-in sucking tube into the victim and secretes an anti-coagulant chemical to keep the blood from clotting so she can offer the blood as nourishment for her babies-to-be. It’s that clear anti-coagulant that contains the Plasmodium parasites that actually cause malaria, of which there are five known species. The most deadly ones are Plasmodium falciparum and Plasmodium vivex. Ironically, malaria is virtually unknown in the temperate climates of the world because of a major campaign to eradicate the mosquitoes that transmit it, staged during World War II after the U.S. and the other Allied governments realized that as many of their soldiers were being killed or incapacitated by malaria as were being killed or wounded in combat. Among the weapons used to end malaria in the developed world was an insecticide called DDT, which also did so much collateral damage it was ultimately banned during the first heady flush of the modern environmental movement, but while it was widely used it did the job. It successfully curtailed the spread of malaria in the United States and through Europe, but malaria remained a threat in the tropics – especially in Africa, South America and India – in nations that had large mosquito populations, didn’t have the resources to mount major mosquito extermination campaigns and weren’t sufficiently on the world’s radar for most people to care.

Research to develop vaccines against malaria has been going on for decades. There are several impediments, however; not only is malaria caused by a parasite (not a bacterium or a virus, like most diseases that have been successfully controlled by vaccination), the parasite has a coating that enables it to enter a cell and infect it. The secret behind R21 – and an earlier, less effective malaria vaccine called RTS,S – is to take a harmless virus, coat it with the same protein coat as the malaria parasite, and inject it into humans in hopes that the vaccine will teach the human immune system to recognize the parasite’s coating and form defenses (antibodies) against it. The first half of the program is a good, though necessarily short, explanation of how malaria works and how the parasite starts the infection in the bloodstream, where it spreads from; the second half talked about the elaborate testing regimen needed to determine whether R21 actually works. The tests were authorized by the World Health Organization (WHO) and followed the rules set forth by the U.S. Food and Drug Administration (FDA): a Phase I trial to determine the drug’s safety, a Phase II trial to determine its efficacy, and a longer-term Phase III trial to test the drug in large numbers of people to determine whether it worked well enough long-term to be worth administering. The last time scientists tried to develop a malaria vaccine, RTS,S, it had reached only 40 percent efficacy – better than nothing but not the 75 percent the scientists were hoping for because that was the WHO’s criteria for licensing the vaccine and getting public and private donors to pay for it. R21 reached 70 to 80 percent efficacy, which the scientists considered good enough for a “win” even though that still leaves 20 to 30 percent of the target populations vulnerable to malaria.