‘Ukraine polio outbreak – is Europe in danger?’
RT: How dangerous for Ukraine and Europe as a whole is the latest outbreak of polio? What are the main concerns here?
Walter Orenstein: The big concern is that Ukraine has fairly low immunization coverage against polio, and that is why this outbreak has occurred. The important thing is rapid aggressive response with vaccination of children achieving high coverage. In terms of Europe, the big issue - Europe is in a good position to protect itself if it continues to get high immunization coverage against polio as long as there are polioviruses in the world; there is risk of importation of those viruses into European countries. So it is important to maintain high routine immunization coverage.
RT: Do you think the outbreak in Ukraine is connected to the current socio-economic situation in the country?
WO: It is possible, although the immunization coverage in Ukraine has been low for some time. So in a sense even before a lot of the more recent developments there is an accumulation of susceptible people. Certainly with the conflict it makes control more difficult… This is different in wild poliovirus; this is called circulating vaccine derived polioviruses. What that means - is this starts with the parent Sabin Oral vaccine virus, and because there are so many susceptible children it is transmitted from one person to another; and it regains both the ability to attack the nervous system and cause paralysis, as well as transmit these wild viruses. The key in Ukraine is to now respond and achieve high coverage which will protect not only individuals in Ukraine, but all around the world including Europe, and again to try and build back their routine immunization system.
RT: Could you be more precise on how the routine immunization coverage in Ukraine should be improved?
WO: Their coverage at best we can tell was estimated only to be about 50 percent of their children were being adequately vaccinated against polio. That is much too low a percentage. So they need to aim for 90 percent or better. And that is the problem: if you don’t vaccinate these children, they grow to older age- still susceptible, and there are fertile ground for introduction of polio viruses that can cause paralysis.
RT: Do you think there’ll more cases of polio in Ukraine?
WO: I think there are very likely to be more cases. It depends on how good their response is. The polio viruses generally don’t cause paralysis. For example, the estimate is only 1,100 – 1,200 infections result in paralysis. The issue is – can they get on top of it quickly enough with campaigns targeting children from birth up to five years with at least three rounds of vaccination, and that is I presume what they are planning right now.
RT: You’ve been working on eradicating polio for years. Can you tell us more about your experience?
WO: The big issue is - Europe had been certified as polio-free. This is a little different than the polio we’re talking about in most of the world which is caused by wild polio viruses. The polio in Ukraine is caused by vaccine viruses that actually mutated or changed and became capable of causing paralysis. It is of concern because these viruses behaved just like the wild viruses, and we need to get on top of it and stop transmission as quickly as possible. The concern clearly is – if there are other places in Europe or elsewhere these people traveling to those places could transport the viruses. So it’s another lesson that we cannot let down our guard - that until polio is completely eradicated we run the risk of polio returning. So we need to keep up our routine vaccination coverage.
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