Researchers Investigate Shedding of H1N1 Flu Virus Among HCWs

The Centers for Disease Control and Prevention (CDC) recommends that healthcare workers infected with pandemic influenza (H1N1) 2009 virus not work until 24 hours after fever subsides without the use of antipyretics. The CDC guidelines for the 2009 influenza season specifically recommend that healthcare workers who have a fever and respiratory symptoms stay home from work for 24 hours after fever subsides without the use of fever-reducing medications. Healthcare professionals who do not have a fever are permitted to work if they use appropriate infection prevention and control practices. Earlier return to work is permitted for healthcare workers who are caring for patients with lesser degrees of immune system compromise who also might be at increased risk for complicated influenza infections.

Meagan Kay of the CDC and colleagues report on their examination of the association between viral shedding and fever among infected healthcare workers during an influenza outbreak in the latest issue of Emerging Infectious Diseases. They point to the limited number of studies that have described the duration of pandemic (H1N1) 2009 virus shedding among healthy persons, as estimated by the presence of viral RNA detected by real-time RT-PCR or viable virus detected by culture. (For example, a study by the U.S. Air Force demonstrated that viable virus was present in 24 percent of nasal wash samples from infected military trainees seven days after symptom onset. Another study reported that virus was undetectable by culture five days after symptom onset or by real-time RT-PCR at eight days among 21 of 22 hospitalized patients treated with oseltamivir.)

Participants recorded temperatures daily and provided nasal wash specimens for two weeks after symptom onset. Specimens were tested by using PCR and culture. When they met CDC criteria for returning to work, 12 of 16 healthcare workers (75 percent) had virus detected by PCR, and nine (56 percent) had virus detected by culture. Fever was not associated with shedding duration (p = 0.65). The researchers note that healthcare workers might shed virus when meeting CDC exclusion guidelines, and that further research is needed to clarify the association between viral shedding, symptoms and infectiousness.

Reference: Kay M, Zerr DM, Englund JA, Cadwell BL, Kuypers J, Swenson P, Kwan-Gett TS, Bell SL, and Duchin JS. Shedding of Pandemic (H1N1) 2009 Virus among Health Care Personnel, Seattle, Washington, USA. Emerging Infectious Diseases. April 2011.