However, Israel monitors for the presence of polio and has discovered polio virus in sewage in several cities. This discovery triggered a massive polio vaccination campaign in children, most of whom had already been vaccinated against polio with the killed injected vaccine. Now they are revaccinating children with the live oral polio vaccine in an attempt to stop the spread of polio virus. This live vaccine had been abandoned because it can cause polio infection in recipients and in caregivers who come in contact with the virus passed in feces when changing babies' diapers. It is inevitable that the vaccine campaign will cause a few cases of polio, which will then be blamed on the wild virus "proving" that the vaccine campaign was necessary.