Abstract：Objective To investigate the epidemic characteristics and possible causes of an influenza outbreak caused by nosocomial infection so as to provide a scientific basis for epidemic situation control. Methods The case definition was developed, and then the cases were searched. Case investigation and field hygiene investigation were conducted by using field epidemiological survey methods. The epidemic characteristics and possible causes of the outbreak were analyzed by using descriptive epidemiological method, case-control study, the clinical features of the cases and the laboratory Results of virus nucleic acid detection. Results There were 9 cases of laboratory diagnosis and 8 cases of clinical diagnosis reported during this nosocomial infection. The peak of the incidence was on May 31st. The shortest latency period was 1 day, and the longest 4 days, with the average being 2.6 days. No statistically significant difference was found in the incidence rate between the inpatients living on the first floor and nurses (P=0.695).Whether the nurses worked on the first floor had a significant influence on the incidence (OR=6.60,95%CI:1.48-29.36). 10 patients’ specimens were collected to perform RT-PCR detection, and 9 were positive for influenza H3N2 virus nucleic acid. All nurses had no history of influenza vaccination. Through the isolation and treatment of the cases, all the cases were stable or cured. And no new case was found in the longest latency period. Conclusions This is an outbreak of influenza A (H3N2) epidemic, which is caused by a newly admitted patient who is considered as the source of infection, and is spread by respiratory droplets between nurses and other inpatients. Timely isolation and treatment is one of the most important prevention and control measures. Nurses may be one of the main disseminators inducing the influenza outbreak. Professionals of medical institutions should receive a flu vaccination so as to enhance the immunity or alleviate flu symptoms.
2018, Vol. 25 
