005180000a22001570004500003000900000005001700009110006900026245008000095020001800175264004900193300000800242041000800250650004000258650003300298650002900331PH-MaWHO20241108112311.0  aWorld Health Organization Department of Vaccines and Biologicals  aWHO vaccine-preventable diseases : monitoring system : 2001 global summary.  aWHO/V&B/01.34  aGeneva : bWorld Health Organization,c2001.  a1v.  aeng  aEpidemiologic surveillancexMethods  aCommunicable disease control  aImmunizationxStatistics