Before COVID, many other diseases plagued our world...and they haven’t simply gone away. In
fact, the current pandemic has actually made many other epidemics even harder to treat
and control. But there’s good news on the horizon, because recent breakthroughs are
bringing us more immunity than we’ve ever had before to one of the world’s oldest
and deadliest infectious diseases. That disease is malaria.
Malaria affects over 200 MILLION people and kills about half a million people every year.
It’s actually one of the world’s leading causes of death for children under 5.
And it’s been around for literal millenia. But we still don’t have a handle on it...
Why is that?
Well, malaria is caused by a parasite—a group of them, actually, called Plasmodium.
These parasites are transmitted by some species of mosquitoes.
When an infected mosquito bites a human. The mosquito regurgitates some of the parasite
into the human’s bloodstream...ta-da, infection. From there, the parasites move to your liver,
where they multiply and mature into the form that can move on to infect your red blood cells.
This is the point at which you develop symptoms—fever, chills, headache, vomiting,
muscle pain. In severe cases, this can lead to trouble breathing, organ failure, and even death.
And the measures we currently have to combat this disease aren’t really that great. Antimalarial
drugs can be really rough on your body. We actually give them not only to treat
the disease, but also to prevent it...And one analysis found that these drugs may only be
up to 72% effective at preventing malaria. PLUS, the darn parasites keep developing
resistance to many of these drugs. We also have tools that target the mosquitos
themselves instead of the parasite
like insect nets and bug spray.
And these play a huge role in malaria prevention, but the availability of
all of these tools is easily disrupted by things like civil unrest or...the COVID-19 pandemic.
So, a more long-acting, more effective solution would be HUGE.
A solution like a vaccine. The thing is,
there is no approved vaccine for any parasitic disease of any kind. See, when we make a vaccine,
we’re trying to get your body to protect itself by introducing it to the parts of the pathogen that
would make you sick, what’s called an antigen. For COVID, that’s the viral spike protein.
But parasites are generally much more complex pathogens than bacteria or viruses,
so those antigens are more complicated. But there are some options on the horizon.
The most advanced candidate so far is called Mosquirix. It has actually been approved by the
European Medicines Agency and passed through phase III trials,
but it’s not yet approved by the World Health Organization.
It contains one of the parasite’s main surface proteins as the antigen,
and that's produced in a lab by inserting
the DNA that codes for the antigen into a microbe, like a yeast. The microbe produces that antigen,
we put it into the vaccine, and that antigen activates your immune system
against the parasite.
But this vaccine doesn’t provide full protection—it’s around 30-40% effective
in some trials
against malaria infection over the course of about 4 years, and that decreases over time.
Another vaccine that works in a really similar way, called R21, has come onto the scene
more recently and improved on the amount of protection, with some studies showing up to 77%
effectiveness, but it’s still early in its trial stages.
The NIH recently tested another kind of vaccine, a live-attenuated type.
That means it contains the whole, live parasite, but it's been weakened by something—in this case,
by radiation—to make it so it can't actually infect you.
This candidate can provide
100% protection, but only against the exact same strain of parasite that’s included in the vaccine.
Because there are many species of Plasmodium, and within species there are different strains, this
vaccine provides incomplete protection against strains that are different from the parasite
that’s in the shot. And the newest member to join this cast of characters is one we’re all used to
hearing about these days...because it's an mRNA vaccine.
Using the same technology that’s behind the
Pfizer-BioNTech and Moderna COVID vaccines, this malaria vaccine candidate contains mRNA that
codes for the antigen—one of the parasite’s surface proteins.
Instead of having the actual protein itself in the
vaccine, like the Mosquirix and R21 candidates do,
or having the whole live parasite in it, like that NIH vaccine,
this vaccine contains just the mRNA,
and your cells are what’s making the protein. BioNTech recently tested this vaccine
in mice, where it yielded 88% protection. The company has its sights set on having the
world’s first mRNA vaccine for malaria available for use in humans by 2022.
Now, all of these candidates still face many hurdles, from having enough facilities to make
each kind of vaccine, to the logistics of getting them to the people who need them.
And while none of them are licensed and on the market yet, we could be just a few
years away from the world’s first ever approved parasite vaccines—maybe letting us swat malaria
away for good, and changing the world forever.
If you want more positive infectious disease news,
check out this video over here, and for more buzz on all things vaccine, make sure you
subscribe to Seeker. If you have another public health topic you want us to cover,
leave us a comment down below and as always, thanks for watching. I’ll see you next time.