Sept. 8, 2015 – While the UN has set 2018 as its target for the global eradication of polio the confirmation last week of cases in Ukraine – which left two children aged four years and ten months paralyzed for life – is worrying proof that if vaccination rates slip then the virus will reemerge.
Ukraine had only a 50 percent polio vaccination coverage rate in 2014 but that had reportedly slipped to 14 percent this year due to low or no availability of vaccine doses and strong anti-vaccine sentiment.
The Global Polio Eradication’s International Monitoring Board (IMB) issued a warning less than a year ago that “the risk in Ukraine is of deep concern.”
The Oct. 2014 warning added that, “The last thing the global polio eradication program now needs is the re-emergence of polio in a place distant from its two epicentres and threatening to reverse the certified polio-free status of a whole region (in this case Europe).”
Polio incidence has been reduced by 99.9 percent since 1988 when there was an estimated 350,000 cases to just 37 cases in 2015 as of Sept. 2.
The two Ukraine cases occurred in the southwest of the country which shares borders with Hungary, Poland, Romania and Slovakia. To contain the spread, the World Health Organization says two million children in Ukraine under the age of five must begin to get vaccinated within two weeks of the confirmed cases.
Children typically get four doses of the polio vaccine, at ages two months, four months, 6-18 months and a booster does at 4-6 years.
The children in Ukraine were infected with a vaccine-derived type of polio. Such cases are rare – there have only been only 500 cases of paralysis from circulating vaccine-derived polio virus type 1 (cVDPV1) from 2001-2011 while the oral polio vaccine has prevented some 3.5 million cases of paralysis – but the most important risk factor for emergence and spread of cVDPV1 is immunity gaps resulting from low immunization coverage.
The European Center for Disease Control (ECDC) in a bulletin last week said, “It is likely that the cVDPV1 strain has been circulating for many months in Ukraine and that the virus could be found in other parts of the country.”
“Based on experiences from other similar events in the past, we can assume that the risk of more children presenting with paralytic poliomyelitis in Ukraine is high and that it will remain high until large-scale supplementary immunisations have been implemented, in accordance with WHO recommendations for the control of polio outbreaks,” the bulletin added.
It said there is risk of the virus being imported into EU countries from border areas but the risk of it resulting in paralysis is low given widespread vaccine coverage. However, the ECDC warned that there are pockets of under-immunized or unimmunized people in the European region, and said Bosnia and Herzegovina, Romania and Ukraine are at high risk for further polio spread.
– Denis Fitzgerald @denisfitz