In August 2009, NIOSH received an HHE request from the director of the internal medicine residency program at UUSM concerning the exposure of internal medicine housestaff to the pH1N1 virus. A number of internal medicine housestaff were reportedly diagnosed with pH1N1 in June 2009, and more housestaff were reported to have ILI, leading to significant absenteeism in this program. The exact extent of the disease, risk factors leading to infection, and modes of transmission among the internal medicine housestaff were unknown at the time of the request. In August-September 2009, we performed a cross-sectional study to examine pH1N1 exposure; determine the prevalence of pH1N1 infection and ILI; identify modes of transmission; and identify risk factors for infection among the internal medicine housestaff, cardiology fellows, and pulmonary and critical care fellows who were in the program at any time from May 1-June 30, 2009. We also assessed knowledge, attitudes, and practices towards influenza infection control measures. We made a site visit to UUSM and the four associated medical centers in September 2009, to meet with housestaff, fellows, and staff members at each of the four medical centers to learn about their experience during the early 2009 pH1N1 pandemic. We found that most of the 88 responding physicians reported exposure to individuals with pH1N1 or ILI either at work or outside of work. Most respondents reported having contact with a patient with confirmed or probable pH1N1 or ILI but also reported contact with ill coworkers at work and outside of work. Thirteen cases of ILI, with five laboratory-confirmed diagnoses of influenza A, occurred in responding physicians in May-June 2009. Transmission likely occurred at work and outside of work. We concluded that all four medical centers were appropriately using the occupational health hierarchy of controls approach to prevent influenza transmission within their centers and to prevent exposure of healthcare personnel. Comprehensive programs were in place, and innovative methods of infection control had been implemented with respect to engineering and administrative controls. However, our survey results show some gaps in infection control knowledge, incomplete exclusion of ill housestaff and fellows from work, and gaps in adherence to PPE use. We recommend that the residency and fellowship programs have procedures for tracking ill and absent housestaff and fellows. The programs should also develop a written plan for staffing in the event of a pandemic or other emergency. Housestaff and fellows should be encouraged to self assess for symptoms. Housestaff and fellows with febrile respiratory illness should be excluded from work according to the most recent CDC guidance, found at https://www.cdc.gov/flu/professionals/infectioncontrol/healthcaresettings.htm
. They should also be encouraged to avoid social events outside of work. Education and training of housestaff and fellows should be provided at least annually regarding the evaluation, diagnosis, treatment, and complications of patients with symptoms of influenza; the recommended isolation precautions at each of the four medical centers; proper hand hygiene; and the proper donning, use, and removal of recommended PPE. Housestaff, fellows, and all medical center employees should continue to be required to receive the annual seasonal influenza vaccine as part of the comprehensive influenza infection control strategy. The vaccine should be made available to all housestaff and fellows at their assigned medical centers. Signage indicating appropriate isolation precautions should be placed outside of patients' rooms concurrent with placement of patients in rooms. HCP entering the room of a patient in isolation precautions for influenza should be limited to those performing patient care activities. A respiratory protection program should be developed, implemented, and maintained for all housestaff and fellows to protect against airborne infectious agents. All housestaff and fellows should receive training, receive medical clearance, and undergo fit testing as specified in the OSHA Respiratory Protection Standard (29 CFR 1910.134). PPE, including gloves, gowns, surgical masks, N95 filtering facepiece respirators, and eye protection, should be made readily available near patient rooms according to hospital guidelines. PPE use should be emphasized when caring for critically ill and noncritically ill pH1N1 and ILI patients. The medical centers should ensure appropriate stockpiles of N95 respirators and other PPE in preparation for potential outbreaks of airborne infectious agents.