Cases of polio in Syria and Israel could cause an outbreak in Europe, researchers have claimed.
Two doctors, writing in the Lancet, claim that because only one in 200 people infected with poliovirus develops paralysis, it could take a year before an outbreak is detected.
The researchers write that although it is the recommendation of the European Centre for Disease Prevention and Control, vaccinating only Syrian refugees would be ‘insufficient’.
To prevent an outbreak in Europe, the researchers believe use of the oral polio vaccine (OPV), rather than the inactivated polio vaccine (IPV), would be best suited to curb the possible outbreaks.
However, the vaccine was discontinued in Europe because it can lead to cases of acute flaccid paralysis, the main symptom of polio.
Although IPV is highly effective at preventing polio disease, it does not give the same level of protection against the virus as the oral vaccine, so vaccination coverage needs to be very high.
The doctors say that countries with low coverage such as Austria (83%) and Ukraine (74%) risk a sustained outbreak should the virus be introduced via refugees fleeing Syria. Polio vaccine coverage in the UK is at 95%.
Professor Martin Eichner, from the University of Tubingen told the BBC: "Wild poliovirus has also been found in sewage in Israel and from samples taken from some symptom-free individuals since February 2013. Although there have been no cases of polio in Israel, tourists could risk bringing the infection to other countries."