How Can Polio Seasonality Be Used to Eradicate the Disease Worldwide?

Micaela Martinez, PhD, postdoctoral fellow in the Department of Ecology and Evolutionary Biology at Princeton University, discusses how vector seasonality can potentially be used to eradicate polio worldwide.

Interview Transcript (slightly modified for readability)

“Polio is a fairly unique disease in that the outbreaks typically happen in the summertime, so [in the absence of vaccination] we see extremely explosive polio outbreaks that occur every single summer. We had that in the United States before we launched the first polio vaccine.

Right now, the way that the global polio eradication initiative works in developing countries is that there are what are called national immunization days. In the developed world, if you live here in the United States [or in] Europe, typically children are given their polio vaccines as part of the infant vaccination schedule; they go to routine primary care and that’s how they’re vaccinated. That same luxury does not exist in all parts of the world, and in many developing countries, children rely on national immunization campaigns to get their vaccines.

In terms of the polio vaccine, what happens is, there will be a couple [of] periods throughout the year, typically during a couple of months of the year, where vaccine workers go out into communities [and] the goal is to find every child under 5 years old and give them a vaccine regardless of whether or not they’ve had the polio vaccine before. If they’ve never had it, then it’s their first time getting vaccinated; if they’ve had it before, then great, you’re just boosting their immunity.

Typically, these national immunization days, which can mean giving out millions and millions of doses of vaccine, will happen during particular months of the year, and those months are chosen based on logistical constraints. The oral polio vaccine has to be kept cold, so lots of times they go out during times of the year when it’s relatively cool, but some of the work that I’ve purposed is that if you think about polio’s transmission being seasonal, then you have a time of the year when polio transmission is very low and a time of the year when polio transmission is really high. During that time of the year when polio transmission is low, there are very few infections in the population and if your goal to eradicate polio is to drive this pathogen to extinction, then what you need to do is you need to knock out those last few cases in a population. During that low transmission season, [when] there are very few infected individuals in the population, then the virus is essentially vulnerable to being driven to extinction.

My idea has been if you know what time of year transmission is low and the virus is vulnerable to being driven to extinction, then we can go out, launch these massive immunization campaigns during that time, hit the virus, and knock it out locally. If you do that in all of the places that have polio simultaneously, then you can have a polio-free world.”