H1N1 Influenza at University of Minnesota Medical Center/University of Minnesota Amplatz Childrens' Hospital 2009-2010

Background: During the year April 26, 2009-April 30, 2010 Minnesota experienced the 2009 H1N1 Influenza Pandemic. The first hospitalized case in MN occurred on 5/2/09. During this pandemic period patients were actively screened at UMMC/UMACH for influenza like illness (ILI). We summarize the results of 524 patients who had screening tests sent for influenza at our institution during the pandemic.

Objective: Analyze the data gathered at our institution during the influenza pandemic period on screening patients with ILI. Describe the clinical features of our patients with laboratory confirmed 2009 H1N1 influenza.

Methods: During the pandemic 524 patients had influenza testing done at UMMC/UMACH. The Infection Prevention Dept. maintained a database of all patients with lab tests sent for influenza during the study period. We undertook a detailed chart review to abstract data on presenting signs and symptoms, treatment, admission, and mortality.

Results: 357 adults were screened for ILI. 121/357 (33.9%) tested positive. 167 children were screened for ILI. 97/167 (58.1%) tested positive. Of all the patients with lab confrimed influenza A, 52/121 (43%) adults and 18/97 (18%) pediatric patients were PCR positive for 2009 H1N1. 69/121 (57%) of the adults required hospital admission, 30/121(24.8%) required ICU admission and 14/121 (11.6%) died. 8/121 (6.6%) of adults died due to H1N1. 17/121 (14%) adults required mechanical ventilation. Of those 17 who were intubated,  8/17 (47%) died. For the pediartic patients 42/97 (42.3%) were admitted to the hospital. 7/97 (7.2%) required ICU admission.  3 pediatric patients required mechanical ventilation, 1/3 (33.3%) died. 2/97 (2.1%) of pediatric patients died due to H1N1. For adults with  confirmed influenza A the most common presenting complaints were fever and cough each at ~80%, followed by dyspnea ~50%. For pediatric patients, fever ~95% and cough ~80% were also the most common presenting complaints, followed by rhinorrhea ~50%. For adults the top 5 underlying conditions were, in order of frequency, obesity, hypertension, immunosupression, asthma and metabolic disorder. For pediatric patients the top 5 underlying conditions, in order of frequency, were immunosuppression, obesity, chronic cardiovascular disease, asthma and chronic renal disease. 10 adult and 2 pediatric cases were hospital acquired the rest were all community acquired.

Conclusions: During an influenza pandemic fever and cough were effective screening criteria for ILI. During the pandemic period 33.9% of the adults screened and 58.1% of the pediatric patients screened for ILI tested positive for influenza A. All patients with ILI were to be preemptively isolated in modified droplet precautions while awaiting lab results. This was overall an effective approach for preventing nosocomial transmission of influenza, with a total of 12 hospital acquired case still occuring though.