Investigation and analysis of an outbreak of influenza B/Victoria

Objective The present investigation was conducted to understand the outbreak of in- fluenza B/Victoria at Qinghua Middle School in Lianshui County of Jiangsu Province and analyze the epidemiological characteristics of the outbreak.Methods The data from influenza case questionnaires were statistically analyzed.The specimens of throat swab of patients in acute phase were detected for RNA of influenza B by RT-PCR.Results Thirty-seven influenza B cases were reported at Qinghua Middle School in Lianshui County from February 23 to March 1,2006,the attack rate being 4.46 %. The patients' ages ranged from 13 to 17,the sex ratio being 6.4:1.Influenza B RNA was detected from 5 patient's specimens of throat swab by RT-PCR,2 of which influenza B/Victoria were isolated. Conclusion It is recommended that the influenza vaccine should contain B/Victoria,and the influen- za surveillance should be further improved in epidemic seasons.