Conflict preventing polio eradication
For a long time the World Health Organisation have been trying to eradicate polio and in the last decade they've got to within a whisker of making it happen; but the infection is still stubbornly lurking in just three countries. So why is this end-game playing out for so long? The countries in question have had recurring conflicts and wars, which people have suggested could hamper vaccination efforts and allow the disease to bounce back. But there was no evidence to support this claim. Now there is, as Chris Smith heard from Amol Verma…
Amol - Polio is a virus that’s transmitted between humans and it causes paralysis. There was a time in the world where there were 350,000 cases of paralysis related to polio virus infection every year. Effective polio vaccine was developed in the middle of the 1900s and was released to incredible fanfare with press releases and media attention. It was a huge celebrated event for humanity that they had a vaccine.
Chris - This should be, in theory, an eradicable disease shouldn’t it? It should be possible to wipe polio out?
Amol - Yeah well, in theory we should be able to delivery this effective vaccine to enough people that would interrupt the transmission of the virus between one human to another and then the virus has nowhere else to go. It has nowhere else to live and, in theory, it could be wiped off the face of the Earth. Overall, the efforts been remarkably successful so 99.9% of the world’s polio cases no longer occur. We are now running into the last stretch, the last mile of the eradication effort. There are only three countries that have not yet eradicated polio - Nigeria, Pakistan and Afghanistan.
Chris - What’s stopping us getting this thing over the line?
Amol - There are many challenges, logistical and otherwise, to eradicating polio from these regions but one of the barriers that has often been cited is the effect of insecurity or conflict.
Chris - Why should that make a difference to the process in these places?
Amol - It may make it more difficult to deliver vaccine supplies. It may make it difficult to establish trusting relationships and partnerships with communities. It may induce mass migration, so when you have moving populations that could make it harder to vaccinate people.
The theory that our study investigated is whether insecurity makes it more difficult for vaccinators to access the children who need to be vaccinated and, indeed, we found that that was the most important problem.
Chris - How did you you do this; where did you do it and what did you actually do to find that out?
Amol - We examined polio vaccination efforts and polio cases in North West Pakistan. That’s the region of pakistan that borders Afghanistan and has been troubled by conflict and its one of the most important remaining reservoirs of polio in the world. We linked publically available data about conflict related security incidents with data about vaccination coverage and vaccination rates, as well as data about the number of polio cases in that region.
Chris - So you’re looking for an association: if there is some kind of instability or some kind of conflict in this area, is that reflected in a change in vaccination uptake and then the knock-on effect, is there an uptick in the number of polio cases off the back of that?
Amol - Yeah, exactly right. We found a 73% increase in the number of polio cases, and we also found about a 5% reduction in vaccination rates when there was high insecurity.
Chris - Given what you have found, and this does chime very much with what people had been saying is probably what’s going on for a long time, they just couldn’t prove it, now that you can actually hold up this data as objective evidence that this is what’s going on, what can we do about it?
Amol - This does highlight three strategies that could be used. The first is efforts need to be agile and nimble to respond to unpredictable changes in access to vulnerable populations.
The second is that efforts tend to be more effective if you develop trusting relationships with local communities, and so working in in that regard to engage local workers can be effective, and that’s something that the polio eradication initiative in Pakistan has made heroic efforts, really remarkable work in that regard.
The third is to design strategies that can take advantage of narrow windows of opportunity. So design programmes that if you get in, have a narrow opportunity to deliver vaccinations, you deliver a vaccine that is effective in one dose rather than three doses, and that’s the kind of thing that has been introduced in Pakistan with a new injectable vaccine rather than an oral vaccine.