H1N1 Pandemic Influenza Exposures at an Urban Public University-affiliated Hospital in Atlanta

Background: 2009 H1N1 novel influenza emerged as an important public health problem in Atlanta in August 2009.  H1N1 infection control, diagnostic and treatment protocols were distributed to all health care workers (HCWs) at Grady Hospital.  Patients were screened with a simple questionnaire at all intake areas.  HCWs were instructed not to come to work if ill with influenza like illness (ILI). 
Objective: 1) To describe the epidemiology of H1N1 influenza at Grady Hospital between August and mid-November 2009;  2) To describe the number of exposure episodes due to H1N1 and the need for oseltamivir prophylaxis; and 3) To evaluate the ability of current surveillance methods to detect ILI among HCWs and patients.

Methods: Lab confirmed influenza cases were prospectively followed between August and mid-November.  The GA Public Health Lab performed PCR for the 2009 H1N1 on nasopharyngeal specimens from patients with ILI.  The number of influenza exposure episodes (patients with lab-confirmed influenza who were not in isolation for the duration of admission) was prospectively followed by the Grady Epidemiology/Infection Control (IC) Dept. The IC Dept. also tracked HCWs who self reported ILI. Exposed patients and HCWs were offered oseltamivir prophylaxis based on CDC guidelines.
Results: A total of 35 patients (mean age = 29.4 years) were admitted to Grady and diagnosed with lab confirmed H1N1 influenza.  Ten patients required ICU care.  There were no deaths due to influenza.  Four cases (11%) led to exposure episodes resulting in 15 persons (2 patients, 9 HCWs, 4 family members) offered oseltamavir prophylaxis and no secondary cases were identified.  No exposures from lab confirmed H1N1 patients occurred after active surveillance was initiated to ensure isolation of all patients from whom diagnostic specimens were obtained.  Fifteen HCWs (4 attending physicians including 2 in Internal Medicine [IM], 6 IM residents, 2 student on IM rotations, and 3 Grady employees) reported an ILI to the IC Dept including 6 HCWs who came to work ill or developed symptoms at work.  The 6 HCW ILI exposure episodes resulted in recommendations for 53 individuals (18 patients and 35 HCWs) to take oseltamivir prophylaxis. There were no secondary H1N1 cases.
Conclusions: IC efforts effectively identified patients admitted with an ILI that was proven to be H1N1 influenza.  Active surveillance of patients who had a diagnostic test performed enhanced program efficiency by minimizing subsequent H1N1 exposure episodes.  Further approaches are needed to better establish surveillance mechanisms for HCWs with ILI.  There was a significant reporting bias for the IM service and a lack of cases reported by other HCWs.  Despite these limitations, HCWs who were ill at work with an ILI caused more exposure episodes than patients (9 vs 4 per ill individual).  Additional studies are needed on how to monitor illness among HCWs during a pandemic and how best to keep ill HCWs from coming to work.