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SARS Infection Among Health Care Workers in Beijing, China
To the Editor: Although a large number of health care workers have been known to be infected with severe acute respiratory syndrome (SARS), the incidence and the modes of infection within this population have not been completely described.
Methods
We examined SARS infection rates among health care workers in the First Hospital of Peking University, Beijing, China, a general hospital with 1147 beds, 29 clinical departments, and more than 2000 staff members. A total of 322 patients diagnosed with SARS were admitted to the hospital from March 24 through May 13, 2003. Diagnostic criteria for SARS were those of the World Health Organization1; IgG tests with a SARS-specific enzyme-linked immunosorbent assay found that 86% of these patients were positive for SARS during the third week of onset and 99% were positive during the fifth week. No other virological test was performed on these patients.
There were few patients with SARS in the first several days of this period, and they were housed in a ward for infectious diseases with adequate rooms and space. The ward soon reached capacity, however, as the cumulative number of patients increased. There was then a severe lack of specialized facility to handle SARS patients in this and other hospitals in Beijing, and patient transfer was impossible. Therefore, a large number of newly admitted patients with SARS were temporarily housed in the emergency department, which was crowded, poorly ventilated, and without separate areas for patients and health care workers. At the time, the emergency department accommodated 47 patients with SARS in a facility designed for a total of 34 patients. Also at this time, the health care workers wore ordinary hospital protective gowns, 16-layer face masks, and gloves. Safety protocol for preventing SARS infection was not strictly followed and the protective measures and the ventilation were inadequate.
Within the following week, 4 specialized SARS wards were opened, each with 3 clearly marked zones of infected, contaminated, and uninfected areas. The patients with SARS were separated from the rest of the hospital and from each other. Specially designated passageways with buffer zones and air-locked doors were installed for health care workers and for patients. Specific protective measures, strict safety protocols, disinfection routines, and training programs were implemented and enforced. These included wearing disposable protective gowns, 16-layer face masks plus 2 surgical face masks, protective goggles, and gloves, as well as strict procedures for putting on and taking off protective clothes sequentially in designated areas, washing hands, and disinfection of the air using ultraviolet light. A ventilation system with a capacity of 47.25 m3/15 m2 was installed in each ward, capable of changing the entire air of the SARS wards 20 times per hour.
During this entire period, body temperature in all health care workers was measured daily. Any increase in body temperature led to a chest radiograph, lymphocyte count, and SARS antibody test.
Results
Among the 770 health care workers who had contact with SARS patients, 2.43% (n = 18) were found to be infected with the virus. The highest rate of infection occurred among nursing assistants (6.67%) who had the closest and the most frequent contacts with SARS patients. Infection rates were lower among nurses (4.78%) and physicians (2.88%). No infection was recorded among other hospital staff. Health care workers working in the emergency department had the highest rate of infection (11.88%). Most (66.67%) occurred within a 3-day period (April 22-24), 8 to 10 days following the first peak of SARS patient admission (Figure 1).
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Figure. Cases of Severe Acute Respiratory Syndrome (SARS) Among Patients and Health Care Workers at First Hospital of Peking University, Beijing, China, March 24 through May 13, 2003
In the lower panel, the daily total number of admitted SARS patients includes the daily number of admitted SARS-infected health care workers.
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Comment
Our overall health care worker infection rate of 2.43% is lower than that of other major hospitals in Beijing and other areas.2-4 Nonetheless, we attribute the SARS infection among HCWs in our hospital to close and frequent contact with patients with SARS, poor ventilation, lack of enforcement of safety procedures, and inadequate protective measures. The major outbreak of SARS infection among health care workers did not occur until 1 month after admission of the first patient with SARS, when a large number of such patients were housed in the underequipped and underprotected emergency department. We attribute the successful elimination of the spread of in-hospital infection to decisive protective measures and to strict safety protocols for cutting off air transmission of the SARS virus between patients with SARS and hospital staff. With the above measures, even though no negative pressure was instituted in our specialized SARS wards and no N95 face masks were used, no infection occurred thereafter. Our experiences expand on the available literature concerning in-hospital SARS outbreaks,5 identify the possible cause for in-hospital SARS infection, and suggest that simple protective measures and strictly enforced safety protocols are sufficient to control the in-hospital spread of SARS.
Editor's Note: Dr Gu is the corresponding author of this Research Letter (e-mail: jgu{at}privatedoctor.org).
Liuyi Li, MS;
Suhua Cheng, BS
The First Hospital
Peking University
Jiang Gu, MD, PhD
School of Basic Medical Sciences
Peking University
Beijing, China
1. World Health Organization. Preliminary clinical description of severe acute respiratory syndrome (SARS). Available at: http://www.who.int/csr/sars/clinical/en/. Accessed March 21, 2003.
2. Lee N, Hui D, Wu A, et al. A major outbreak of severe acute respiratory syndrome in Hong Kong. N Engl J Med. 2003;348:1986-1994.
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3. Drosten C, Günther S, Preiser W, et al. Identification of a novel coronavirus in patients with severe acute respiratory syndrome. N Engl J Med. 2003;348:1967-1976.
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4. Cumulative number of reported probable cases of severe acute respiratory syndrome (SARS). Available at: http://www.moh.gov.cn/zhgl/ygfb/1200305180044.htm. Accessed May 18, 2003.
5. Ofner M, Lem M, Sarwal S, Vearncombe M, Simor A. Cluster of severe acute respiratory syndrome cases among protected health-care workers—Toronto, Canada, April 2003. MMWR Morb Mortal Wkly Rep. 2003;52:433-436.
PUBMED
Letters Section Editor: Stephen J. Lurie, MD, PhD, Senior Editor.
JAMA. 2003;290:2662-2663.
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