Respiratory illnesses in Canadian health care workers: a pilot study of influenza vaccine and oseltamivir prophylaxis during the 2007/2008 influenza season

Background Data regarding both rates of acute respiratory illness in health care workers and experience with long-term antiviral prophylaxis are sparse. Objective To determine the efficacy and tolerability of oseltamivir prophylaxis versus seasonal influenza vaccine for the prevention of influenza among health care workers. Methods We conducted a pilot, randomized control study during the 2007/2008 influenza season in a tertiary care setting. Adult health care workers 18-69 years of age were recruited and randomly assigned in a 4: 1 ratio to receive either oseltamivir (Tamiflu (R); Roche) 75 mg once daily prophylaxis or seasonal influenza (Fluviral (R)) vaccine. Results Of 56 adults enrolled, 12 received vaccine and 44 received prophylaxis. Incidence of symptomatic laboratory-confirmed influenza was similar for participants in the vaccine and prophylaxis arms (17% and 24%, respectively; P = 0.71). Participants who developed an acute respiratory illness during the study period reported working 85% of scheduled work days, and 29% stated that they worked despite feeling miserable because they were too busy to stay home. Of 42 participants who initiated oseltamivir prophylaxis, four discontinued it owing to side effects. Median duration of oseltamivir prophylaxis was 121 days, with 34 (81%) continuing >= 12 weeks. Conclusions During an extended season of suboptimal vaccine match, 22% of health care workers receiving antiviral prophylaxis or seasonal influenza vaccine developed symptomatic laboratory-confirmed influenza. Long-term antiviral prophylaxis against influenza was generally well tolerated with good compliance.