Lack of SARS transmission among public hospital workers, Vietnam - SARS Transmission

Emerging Infectious Diseases, Feb, 2004 by Le Dang Ha, Sharon A. Bloom, Nguyen Quang Hien, Susan A. Maloney, Le Quynh Mai, Katrin C. Leitmeyer, Bach Huy Anh, Mary G. Reynolds, Joel M. Montgomery, James A. Comer, Peter W. Horby, Aileen J. Plant

The severe acute respiratory syndrome (SARS) outbreak in Vietnam was amplified by nosocomial spread within hospital A, but no transmission was reported in hospital B, the second of two designated SARS hospitals. Our study documents lack of SARS-associated coronavirus transmission to hospital B workers, despite variable infection control measures and the use of personal protective equipment.

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Vietnam was one of the first countries affected by the global severe acute respiratory syndrome (SARS) outbreak and on April 28, 2003, was the first country to be removed from the World Health Organization (WHO) list of SARS-affected countries. Sixty-one patients with laboratory-confirmed SARS were hospitalized in two hospitals, six of whom died; including the index case-patient. All case-patients were epidemiologically-linked to the index case-patient, and most outbreak amplification occurred within one hospital. We investigated whether nosocomial transmission occurred among healthcare workers in the second hospital.

The Study

The SARS outbreak in Vietnam began with the admission of a traveler from Hong Kong on February 26, 2003, to hospital A, a 56-bed, three-story, privately owned and expatriate-operated facility located in Hanoi. Within 2 weeks, extensive nosocomial transmission of SARS occurred in workers, patients, and visitors in hospital A. On March 12, hospital A was closed to new admissions except for sick hospital A workers. On that date, the 120-bed, six-story public hospital B began admitting patients with suspected and probable SARS. Hospital B treated 33 patients with laboratory-confirmed SARS between March 12 and May 2, 2003, the discharge date of the last patient (Figure). Of these, 23 were admitted directly to hospital B, and 10 were transferred from hospital A to hospital B on March 28. Many of hospital B's 33 patients were exposed to SARS as patients or visitors in hospital A.

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No nosocomial SARS-associated coronavirus (SARS-CoV) transmission was reported in hospital B, and none of its 117 healthcare workers (defined as all staff working in the hospital building during the SARS outbreak) became ill with a SARS-compatible illness. This situation occurred despite obvious challenges to infection control. When hospital B began admitting patients, visitors were not tightly restricted, the main elevator was out of service, and families and workers often used the designated patient elevator. Researchers (K.C.L., H.Q.N.) and infection control advisors working daily on the hospital B wards reported variable infection control and patient isolation, particular[y during the early weeks. On March 19, formal infection control training was organized and substantial technical support and supplies arrived from WHO, Medecins Sans Frontieres-Belgium, and the Japan International Cooperation Agency. Systems were established to restrict visitors, and entry guards and Medecins Sans Frontieres' advisors were tasked with distributing and monitoring personal protective equipment, such as N95 masks, gloves, gowns, and hand sanitizer. Two of the authors of this article (K.C.L., H.Q.N.), who worked daily on the wards observed that infection control practices improved considerably after these interventions.

To help researchers determine whether SARS-CoV transmission occurred among hospital B healthcare workers, staff were offered serologic testing from May 12 to 14 and were asked to complete a short questionnaire in Vietnamese. Participants provided written consent and answered questions about demographics, level of contact with SARS ease-patients, and personal protective equipment use during the busiest week of patient admissions (March 12 19) and the remaining weeks of the outbreak. Serum specimens were analyzed at the National Institute for Hygiene and Epidemiology, Hanoi, and at the Centers for Disease Control and Prevention, Atlanta, by indirect enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence (IFA) on Vero E-6 cells infected with SARS-CoV (1). Data were double-entered into Excel and analyzed with SAS Version 8.0 (SAS, Inc., Cary, NC).

Of 117 hospital B healthcare workers, 108 participated (92.3% response rate). According to the hospital director, all 9 nonparticipants remained well, and none had a history of SARS-like illness. Among participants, 62 (57.4%) respondents worked on the SARS wards (Table). Most (85.5%) were physicians and nurses. During the first week of SARS patient care in hospital B, 39 (62.9%) of SARS ward workers reported working in SARS-patient rooms for >6 hours on their single busiest day. Of the 62 workers, 58.1% and 64.5% reported being in SARS patient rooms during medication nebulizer treatment, and 65% reported being in patient rooms during noninvasive positive pressure ventilation.

All 62 SARS ward workers reported wearing masks during the outbreak. All but one respondent wore a mask "always" or "usually" while in SARS patients' rooms. However, during the first week of SARS patient care in hospital B, 43 ward workers (69.4%) reported wearing only a cloth or surgical mask, often in combination. All 62 SARS ward workers reported using an N-95 mask after March 19, although only 56 (90.3%) reported "always" or "usually" using a mask while in SARS patients' rooms. Respondents reported using gloves 77.4% of the time before March 19 and 75.8% after March 19.