RT Journal Article SR Electronic T1 WHO mulls phase out of vaccine linked to polio outbreaks JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP E1303 OP E1304 DO 10.1503/cmaj.109-4027 VO 183 IS 18 A1 Vogel, Lauren YR 2011 UL http://www.cmaj.ca/content/183/18/E1303.abstract