Influenza: Lessons Learned from an Outbreak, Post-Exposure Prophylaxis and Vaccination Campaigns

ISSUE: Influenza is a serious nosocomial pathogen in high risk patient populations and causes an average of 36,000 deaths per year in the United States. Those at greatest risk of serious complications are persons aged less than 2 and greater than 65, and those with chronic medical conditions. Nosocomial acquisition of influenza should be minimized by effective vaccination, surveillance, and aggressive outbreak abatement. PROJECT: In 2003, a nosocomial outbreak of influenza was detected in the pediatric ICU. Control measures included vaccination of staff, patients and visitors, visitor curtailment and post exposure chemoprophylaxis. A survey of 142 healthcare workers (HCWs) receiving post-exposure chemoprophylaxis revealed that amongst the 69 (49%) respondents, amantadine was poorly tolerated and adherence was poor (41%). The most frequent side effects consisted of insomnia, nausea, diarrhea and dizziness. In response to this outbreak, a comprehensive re-evaluation of the influenza prevention program was conducted. A housewide questionnaire determined barriers to vaccination. An online survey targeted approximately 4500 employees resulting in 1939 completed surveys (response rate of 43%). Of those responding, 542 (28%) indicated they did not receive the influenza vaccine. Of those electing not to receive the vaccine, 153 (28%) indicated that the vaccine was not efficacious, 146 (27%) responded that the vaccine was associated with systemic toxicity, and 125 (23%) responded they were not at risk for influenza infection. Data obtained from the survey was utilized to develop educational material and to address these and other identified issues. RESULTS: Subsequent vaccination campaigns increased the overall rate of vaccination in high risk areas from 78% to 88% (p < 0.0001). In 2005-06, 50% of high risk units achieved vaccination rates of greater than 90%. No cases of nosocomial influenza have been detected since the 2003 outbreak. LESSONS LEARNED: 1) Effective influenza vaccination programs require yearly re-evaluation and strategies for improvement. Vaccination rates of 90% or greater are possible. Convenient vaccine delivery with local unit champions appears important in boosting vaccination rates. 2) Amantidine is poorly tolerated by HCWs, resulting in sub-optimal chemoprophylaxis and alternative (neuramindase inhibitor) chemoprophylaxis should be considered.