摘要：An effective national surveillance system is an essential component of a program for the control ofinfluenza. The National Influenza Surveillance Scheme includes data from sentinel generalpractice consultations for influenza-like illness, laboratory reports of influenza and absenteeismrates from a national employer. The 1999 season peaked between May and September withmaximal activity between July and August. Influenza A was the dominant type in all States andTerritories with influenza A H3N2 viruses predominating and influenza A H1N1 occurringsporadically. There was no evidence of significant drift among the H3N2 isolates (A/Sydney-likestrains) whereas the H1N1 isolates showed significant antigenic changes from the vaccine strainA/Beijing/262/95 and were closely related to a new variant A/New Caledonia/20/99. A small peakin influenza B activity occurred towards the end of the influenza season and isolates remainedclosely related to the vaccine reference strain B/Beijing/184/93
关键词：surveillance; influenza; vaccine; antigenic drift; case definition
