أرسل هذا في رسالة قصيرة: Immunity levels to poliovirus in Lao children and adults before the vaccine-derived poliovirus outbreak: A retrospective study

            ______    _____      ___     ______   
    ___    /_   _//  |__  //    / _ \\  |      \\ 
   /   ||   -| ||-     / //    / //\ \\ |  --  // 
  | [] ||   _| ||_    / //__  |  ___  |||  --  \\ 
   \__ ||  /_____//  /_____|| |_||  |_|||______// 
    -|_||  `-----`   `-----`  `-`   `-` `------`  
     `-`