Shedding of Pandemic (H1N1) 2009 Virus | CDC EID

Volume 17, Number 4–April 2011
Research
Shedding of Pandemic (H1N1) 2009 Virus among Health Care Personnel, Seattle, Washington, USA
Meagan Kay, Danielle M. Zerr, Janet A. Englund, Betsy L. Cadwell, Jane Kuypers, Paul Swenson, Tao Sheng Kwan-Gett, Shaquita L. Bell, and Jeffrey S. Duchin

Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (M. Kay, B.L. Cadwell); Public Health–Seattle and King County, Seattle, Washington, USA (M. Kay, P. Swenson, T.S. Kwan-Gett, J.S. Duchin); Seattle Children's Hospital, Seattle (D.M. Zerr, J.A. Englund, S.L. Bell); and University of Washington, Seattle (J. Kuypers, T.S. Kwan-Gett, J.S. Duchin)


Suggested citation for this article

Abstract
The Centers for Disease Control and Prevention (CDC) recommends that health care personnel (HCP) infected with pandemic influenza (H1N1) 2009 virus not work until 24 hours after fever subsides without the use of antipyretics. During an influenza outbreak, we examined the association between viral shedding and fever among infected HCP. Participants recorded temperatures daily and provided nasal wash specimens for 2 weeks after symptom onset. Specimens were tested by using PCR and culture. When they met CDC criteria for returning to work, 12 of 16 HCP (75%) (95% confidence interval 48%–93%) had virus detected by PCR, and 9 (56%) (95% confidence interval 30%–80%) had virus detected by culture. Fever was not associated with shedding duration (p = 0.65). HCP might shed virus even when meeting CDC exclusion guidelines. Further research is needed to clarify the association between viral shedding, symptoms, and infectiousness.

Health care personnel (HCP) with influenza infections can transmit virus to patients. This finding is of particular concern for patients with underlying medical conditions and places them at risk for serious influenza infections. Understanding the duration of shedding of pandemic (H1N1) 2009 virus detected by rapid culture and real-time reverse transcription–PCR (RT-PCR) among HCP is useful in developing infection prevention measures for the health care setting.

The Centers for Disease Control and Prevention (CDC) created guidelines for infection control in health care settings to prevent influenza transmission from infected HCP to patients and other HCP. (1) These guidelines for the 2009 influenza season (2009 CDC criteria) recommend that HCP who have a fever and respiratory symptoms stay home from work for 24 hours after fever subsides without the use of fever-reducing medications. HCP who do not have a fever are permitted to work if they use appropriate infection control practices (1). CDC also recommends that HCP who are caring for severely immunocompromised patients (e.g., patients with hematopoietic stem cell transplantations) be considered for temporary reassignment or be excluded from work for 7 days from symptom onset or until resolution of symptoms, whichever period is longer (1). Earlier return to work is permitted for HCP who are caring for patients with lesser degrees of immune system compromise who also might be at increased risk for complicated influenza infections.

A limited number of studies 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. A study by the US Air Force demonstrated that viable virus was present in 24% of nasal wash samples from infected military trainees 7 days after symptom onset (2). To et al. reported that virus was undetectable by culture 5 days after symptom onset or by real-time RT-PCR at 8 days among 21 of 22 hospitalized patients treated with oseltamivir (3). Among household cases, Suess et al. reported mean shedding durations by real-time RT-PCR for treated and untreated patients of 5.7 days and 7.1 days, respectively (4).

On September 27, 2009, Public Health–Seattle and King County (PHSKC) in Seattle, Washington, was notified of an outbreak of pandemic (H1N1) 2009 among young, otherwise healthy HCP (medical residents) who had attended a work retreat at hospital A during September 21–25. We conducted an investigation to characterize the influenza outbreak and describe viral load changes, shedding duration, and the association between these factors and fever.

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Shedding of Pandemic (H1N1) 2009 Virus | CDC EID


Suggested Citation for this Article
Kay M, Zerr DM, Englund JA, Cadwell BL, Kuypers J, Swenson P, et al. Shedding of pandemic (H1N1) 2009 virus among health care personnel, Seattle, Washington, USA. Emerg Infect Dis [serial on the Internet]. 2011 Apr [date cited].
http://www.cdc.gov/EID/content/17/4/639.htm


DOI: 10.3201/eid1704.100866


Comments to the Authors
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Meagan Kay, Public Health–Seattle and King County, 410 Fifth Ave, Suite 900, Seattle, WA 98104, USA: email: meagan.kay@kingcounty.gov