Reduction of Seasonal Influenza Transmission among Healthcare Workers in an Intensive Care Unit: A 4-Year Intervention Study in Thailand

OBJECTIVE. To evaluate the feasibility and effectiveness of an influenza control bundle to minimize healthcare-associated seasonal influenza transmission among healthcare workers (HCWs) in an intensive care unit (ICU) equipped with central air conditioning. METHODS. A quasi-experimental study was conducted in a 500-bed tertiary care center in Thailand from July 1, 2005, through June 30, 2009. The medical ICU (MICU) implemented an influenza control bundle including healthcare worker (HCW) education, influenza screening of adult community-acquired pneumonia patients, antiviral treatment of patients and ill HCWs who tested positive for influenza, promotion of influenza vaccination among HCWs, and reinforcement of standard infection control policies. The surgical ICU (SICU) and coronary care unit (CCU) received no intervention. RESULTS. The numbers of influenza infections among HCWs during the pre- and postintervention periods were 18 cases in 5,294 HCW-days and 0 cases in 5,336 HCW-days in the MICU (3.4 vs 0 cases per 1,000 HCW-days; P < .001), 19 cases in 4,318 HCW-days and 20 cases in 4,348 HCW-days in the SICU (4.4 vs 4.6 cases per 1,000 HCW-days; Pp. 80), and 18 cases in 5,000 HCW-days and 18 cases in 5,143 HCW-days in the CCU (3.6 vs 3.5 cases per 1,000 HCW-days; Pp. 92), respectively. Outbreak-related influenza occurred in 7 MICU HCWs, 6 SICU HCWs, and 4 CCU HCWs before intervention and 0 MICU HCWs, 9 SICU HCWs, and 8 CCU HCWs after intervention. Before and after intervention, 25 (71%) and 35 (100%) of 35 MICU HCWs were vaccinated, respectively (P < .001); HCW vaccination coverage did not change significantly in the SICU (21 [70%] of 30 vs 24 [80%] of 30; Pp. 89) and CCU (19 [68%] of 28 vs 21 [75%] of 28; Pp. 83). The estimated costs of US $6,471 per unit for postintervention outbreak investigations exceeded the intervention costs of US $4,969. CONCLUSION. A sustained influenza intervention bundle was associated with clinical and economic benefits to a Thai hospital.