The COVID-19 pandemic has scientists considering a few less-conventional options while vaccines against SARS-CoV-2 are being developed. One option might be the oral polio vaccine. We chatted with one of the researchers proposing the idea — Robert Gallo, M.D. — to understand why vaccine that hasn’t been used in the U.S. for two decades might provide short-term protection against this new coronavirus:
Could a polio vaccine help us fight COVID-19?
When I first heard that idea I thought there’s no way, polio has nothing to do with coronaviruses. Turns out it’s not as crazy an idea as I first thought.
I called up one of the researchers who’s proposing it, Dr. Robert Gallo. Dr. Gallo was one of the co-discoverers of HIV and he is a huge name in biomedical research.
[DR. GALLO] This has a chance. A moment like this is for a decisive action and we think it has a real chance of stopping the epidemic.
[SAM] So how could a vaccine for polio keep you from contracting a totally unrelated disease? Generally speaking, it comes down to what the oral polio vaccine does to your immune system. More specifically, how it interacts with your innate immune system, versus your adaptive immune system.
[DR. OZOG] Think of your favorite spy movie, you know like when the spy is invading the compound, like James Bond’s trying to get in to sneak into the the base of the bad guy the innate immune system is kind of more like the guard dog that’s you know walking around. It’s, it’s not specifically looking for a James Bond but it knows that anybody who comes over the wall wearing a ski mask it needs to get bit.
[SAM] Your innate immune system is the guard dog. It’s not looking for anything specific it just attacks anything that looks dangerous.
[DR. OZOG] I would say the adaptive response is more like a Special Forces sniper. It has the picture of James Bond it, knows what James Bond looks like, and it knows exactly who they’re targeting.
[SAM] When you give someone any form of a vaccine you’re training the sniper. You’re giving your adaptive immune system a picture of the virus and saying, next time you see this kill it.
The oral polio vaccine doesn’t just train the sniper. It also startles the guard dog. That’s because it’s what’s called a live, attenuated vaccine. A live, attenuated vaccine contains a complete virus or bacteria that’s been weakened in the lab.
It wakes up the guard dog and that guard dog is angry. Or, to use actual scientific terms here, it activates your innate immune response.
Unlike the oral polio vaccine the polio vaccine you have injected is not live and attenuated, it’s what’s called an inactivated vaccine. Inactivated vaccines don’t use complete live virus and bacteria. They’re made using a physical process like heat, or chemicals like formaldehyde to inactivate little pieces of bacteria or viruses.
Those pieces, great at building adaptive immunity, but they don’t really
spook the guard dog. So the idea here is that the oral polio vaccine would amp up
your innate immune response which would release that guard dog on SARS-CoV-2.
Now you might be wondering why your innate immune system isn’t just doing that on its own. Why would it need help from a live attenuated vaccine to stop COVID?
So it turns out that SARS-CoV-2 can make your innate immune system act kind of erratically and even block it from responding. That causes lung inflammation and fluid buildup that you would see in severe COVID cases.
Taking the oral polio vaccine might help keep that from happening.
[DR. OZOG] You could fight off the virus early before it really establishes a good infection, and then later on hopefully that’s enough to prevent this inflammatory lung destruction that happens in the in the later process of SARS-CoV-2 infection.
[SAM] So the big question is will the live attenuated oral polio vaccine wake up your innate immune system’s guard dog enough to prevent you from getting COVID-19?
[DR. GALLO] This has a chance, if it works. Am I a hundred percent sure? No, I’m a hundred percent sure of almost nothing, so you know, not a hundred percent sure, but we think it has a real chance of stopping the epidemic.
[DR. NIZET] So I think we’re looking at interventions that might buy us a little bit of time before a bonafide SARS-CoV-2 vaccine emerges in 2021, hopefully.
[SAM] I also want to mention that the oral polio vaccine is not the only live, attenuated vaccine that’s being considered. Vaccines for tuberculosis and measles are also in the mix, and the idea is that they would also boost your innate immune response.
Even in the best case scenario these options are really only going to protect you in the short term, so maybe for a few months at a time. That means that you would have to take them every few months until there’s a vaccine for SARS-CoV-2 available.
[DR. GALLO] And when you develop a very good coronavirus vaccine, which is specific, which is long lasting, that would be great. But the truth of the matter is, it’s certainly not in time for this epidemic, and further truth of the matter is you never can give a date for a vaccine. I mean, I hear a lot of suggestions for about the months will take to get it, but reality is, you have a vaccine when you have a vaccine.
[SAM] So at the end of the day these are really just buying as time. You can buy us even more time by staying home, washing your hands, avoiding large gatherings, keeping your distance from other people, and wearing a mask. Maybe just sit on your couch and binge your favorite American Chemical Society YouTube series.
Stay safe, everyone.