Effect of Ill and Unvaccinated Employees on Influenza Outbreaks In Long-Term Care Facilities: Lessons From the 2007/08 Influenza Season

Background: Influenza can cause substantial illness and death among long-term care facility (LTCF) residents. Vaccination of employees and residents of LTCFs can help reduce the impact of influenza. The Healthy People 2010 objective is to achieve 80% vaccination rate for residents and 60% for staff.  

Objectives: To examine the association of vaccine coverage with outbreak severity as measured by Influenza-like-illness, (ILI) hospitalizations and deaths reported in LTCFs in Pennsylvania during one influenza season.

Methods: Data on influenza outbreaks reported from LTCFs during the 2007/08 influenza season in Pennsylvania were examined to assess the relationship between optimal influenza vaccination rates (the HP 2010 objectives) and ILI, hospitalizations and deaths among residents of LTCFs during outbreaks.

Results: During the 2007/08 Influenza season, 92 outbreaks were reported from 91 facilities involving 591 illnesses, 89 hospitalizations and 8 deaths of residents in total. Vaccination was optimal among employees of 26 facilities (4384 employees) and among residents in 71 facilities (12298 residents). Facilities with optimal resident vaccination rates were less likely to have optimal resident vaccination rates (p=0.0028). Most outbreaks were in facilities with sub-optimal employee vaccination rates (66 vs. 26) and facilities with any ill employees (50 vs. 39). Most hospitalizations were reported in facilities with sub-optimal employee vaccination (38 vs. 10). Employee and resident vaccination rates did not differ based on the size of the outbreak (number of cases) or occurrence of fatalities (3 vs. 4).

Conclusions: These data show that facilities with sub-optimal employee vaccination and ill employees more frequently experience ILI outbreaks with hospitalizations. In addition to promoting “optimal” vaccination among staff, policies for exclusion of ill employees may help reduce excess and severe illness among resident of LTCFs. Data from additional seasons and LTCFs without outbreaks would help confirm these findings.