Recently, polio has received a lot of attention when it suddenly appeared in places that had not seen the disease for a long time. There was a case in New York and virus finds in London sewage. In both cases, vaccine viruses that were actually harmless have turned into dangerous pathogens through a few mutations. And infections have also increased again in other countries. In an interview with the SZ, Aidan O’Leary, who is responsible for eradicating the polio pathogen at the World Health Organization, explains what’s next.
SZ: So far there have been no further cases in London and New York. Is the danger over?
Aidan O’Leary: Overall, the risk in these countries is low because vaccination rates are very high. Nevertheless, there are always individual areas, quasi islands, with insufficiently vaccinated children. As long as they exist, there is always a risk of infection. In the affected cities, we are trying to focus on these islands. It is not enough to just supply vaccines, you also have to ensure that children are actually vaccinated. How well this works depends on how quickly the risk of infection decreases again.
Viewed worldwide, the so-called wild polio cases, which are solely due to the virus and not to vaccinations, have increased significantly again this year. From six last year to almost 30 this year, 20 of them in Pakistan. Why is that?
You have to look at it differently. The disease is only endemic in Afghanistan and Pakistan. In Afghanistan, despite a very difficult humanitarian situation, we have only registered two cases this year. So the trend is clearly downwards – a ray of hope for the program.
In Pakistan, the cases stem from an explosive but localized outbreak in the northwest of the country. They are limited to three districts. In other parts of the country that had previously been badly affected, it was possible for the first time in the history of the program to interrupt endemic transmissions. We also had challenges here. The monsoon flooded a third of the country and left six million people homeless. Nevertheless, we continued the program.
Aidan O’Leary is the World Health Organization Director of Polio Eradication. Born in Ireland, he previously worked in several countries for the United Nations Office for the Coordination of Humanitarian Affairs.
(Photo: GPEI)
But there are also cases again in Africa, which was only declared polio-free two years ago. Can this status still be maintained?
True, we were first surprised by a case of polio in Malawi and then saw more cases in Mozambique. We then found that the focus of infection was not in Malawi but in northern Mozambique. Critical to polio-free status is that these cases are due to the introduction of the virus from Pakistan and not because the virus is circulating in Africa.
How long will it take to make up for this year’s setbacks?
Our goal is to stop infections in Afghanistan and Pakistan by the end of 2023. The target is still achievable, but the next two quarters are crucial. Transmissions typically decrease in the coming months. We must use this time to focus on the affected areas and vaccinate the children there before the next polio season. There is now a unique opportunity to get the job done once and for all and eradicate the virus.
Still, some doubt that the goal of extinction is achievable…
I see it differently and would first look at where we started. In 1988 we had a thousand cases a day in 125 countries. Now we only have a few handfuls of cases a year in two countries. If we ask: are our next goals clear, the answer is yes. If there is a way to achieve these goals, the answer is yes. If we’ve come so far that zero is within reach, why should we throw in the towel now? In my opinion, eradication is doable, despite all the challenges.