“Twenty-five years after it had been dispatched, wild poliovirus [is] back in Israel and spreading fast,” Science magazine reports, adding, “Retrospective analysis of sewage samples has shown that the virus has been circulating since February but, surprisingly, has caused no cases of paralysis.” According to Science, “The country is now scrambling to quash the silent outbreak before it spreads further. … And other wealthy countries, including the United States and the United Kingdom, are watching closely, hoping to draw lessons for their own vaccination and monitoring strategies.” The magazine examines the country’s use of the inactivated polio vaccine (IPV) versus the oral polio vaccine (OPV), which can be more effective at preventing the virus’s spread but “can in rare instances regain its neurovirulence and cause paralysis.” The country has implemented new vaccination campaigns using OPV, but “the virus is still circulating in Israel. The most pressing question now is how much OPV is needed to stop transmission — Israel is gearing up for another national vaccination round with OPV — and how long it will take,” Science writes (Roberts, 11/8).