 Complete the following phrase:  Syria, Yemen, and Somalia are categorized as very-high-risk, and Iraq, Sudan, and Libya are categorized as high-risk, while Pakistan and Afghanistan are the only countries in which the disease remains endemic as of 2019. Since 2007, people administering polio vaccines have been the target of violence in Pakistan. A 2011 US Central Intelligence Agency operation used a hepatitis vaccination program as a cover to search DNA evidence to confirm the location of Osama bin Laden. Following 