Which health care workers were most affected during the spring 2009 H1N1 pandemic?

To identify health care workers most at risk for H1N1 infection before vaccination and compare health outcomes after vaccination.

The indices used to gauge employee health were laboratory-confirmed H1N1 data, laboratory-confirmed influenza A data, and employee sick hours records. In phase 1 of this 2-phase study, absenteeism records for 6,093 hospital employees before vaccine administration were analyzed according to department and employee position during the spring 2009 H1N1 pandemic.

Records of 123 confirmed reports of laboratory-confirmed influenza A or novel H1N1 infections in hospital employees were also analyzed. Two thirds of the H1N1 cases occurred during June (infection rates in parentheses): 34 in physicians and medical personnel (6.7%), 36 in nurses and clinical technicians (2.2%), 39 in Administrative & Support Personnel (infection rate = 1.2%), 3 in Social Workers & Counselors (infection rate = 1.0%), 8 in Housekeeping & Food Services (infection rate = 2.7%), and 3 in Security & Transportation (infection rate=3.9%). When analyzed according to department, the adult emergency department (infection rate = 28.8%) and the pediatric emergency department (infection rate = 25.0%) had the highest infection rates per department.

Of the reported cases of H1N1 in health care workers, 49% occurred in a population that constitutes less than 20% of the total population studied. Physicians and medical personnel had a higher infection rate than other employee positions, whereas ED personnel had the highest infection rate.