<prompt> Major reason for H5N1 not to become a global pandemic isMan to man transmission is rareRoute of transmission is not respiratoryDoes not cause serious disease among humansRestricted to few countries only  <response>: Reasons for H5N1 not becoming Global PandemicAbsence of efficient human to human mode of transmission Major reasonAbsence of replication in humansAbsence of serious disease in humans 