Analysis on the surveillance results of influenza from 2004 to 2007 in Shiyan city

Objective　The present study was conducted to analyze the surveillance results of influenza from 2004 to 2007 in Shiyan city, so as to explore the characteristics of influenza and its epidemic features in Shiyan city and to seek scientific and effective measures of prevention and control. Methods　Perennial pathogenic and epidemiologic surveillance of influenza were conducted, also serological surveillance were conducted in September annually. Results　There was not evident monthly change of the proportion of influenza-like cases at the clinics, with children always more than adults. A total of 302 specimens of influenza virus were separated from the 1449 samples, with the separation rate of 20.84%. The separation rate reached the winter peak and the summer peak respectively in January-March and July-September, with the latter weaker than the former. H3N2 subtype and Victoria of B type respectively caused 9 and 14 of 37 influenza-like outbreaks-Antibody levels of each subtype of influenza virus in healthy people changed every year, and the positive rate of each subtype was consistent with its epidemic situation. Conclusion　Influenza virus was active almost all the year round in Shiyan city, and presented a bipeak model with the winter peak higher than the summer peak; for H1N1and H3N2 subtypes, Victoria and Yamagata influenza virus of B type, the development of the former always went with the weakening of the latter, and vice versa. Full consideration should be given to epidemic characteristics of influenza in China and the complexity of B type influenza virus, and vaccine components should be provided based on this. It is suggested that people in Shiyan city should inoculated with influenza vaccine from October to December each year in time, and that the immunization coverage rate of primary and secondary schools and nurseries should be improved.