Effect of Occupational Exposure on A(H1N1)pdm09 Infection and Hospitalization.

OBJECTIVE: To analyze relationships between occupational exposure and influenza infection and hospitalization during the 2009-2010 pandemic wave and the 2010-2011 influenza seasonal epidemic in Spain.

METHODS: Occupations were classified as high, medium, or low risk of influenza exposure. To assess the risk of infection, 588 outpatient cases of influenza confirmed by reverse-transcription polymerase-chain-reaction (RT-PCR) were compared with 588 outpatients without influenza symptoms. To assess the risk of hospitalization, 337 outpatient influenza cases were compared with 337 inpatient influenza cases.

RESULTS: The high risk of occupational exposure group was composed only of health care workers. After adjustment for age, sex, vaccination status, and predictive variables of influenza infection, patients with a high risk of occupational exposure had an aOR of 2.14 (95%CI: 1.25-3.66) of being an outpatient influenza case and an aOR of 0.43 (95%CI: 0.20-0.95) of being an inpatient influenza case, compared with those with a low risk.

CONCLUSIONS: A high risk of occupational exposure is a risk factor for influenza infection but not for hospitalization.