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October 2003 After a happily quiet summer of no detectable transmission of severe acute respiratory syndrome-associated coronavirus (SARS-CoV), things are beginning to heat up again — fortunately almost solely in terms of preparedness planning. The “outbreak” of SARS in a Vancouver, B.C. nursing home that was described in the media in August proved to be due to a known common cold coronavirus, and not to the SARS-CoV. In early September, however, a case of probable SARS was identified in a 27-year-old postdoctoral student in Singapore; this individual had worked in two medical research laboratories that had worked with SARS-CoV. His infection was due to SARS-CoV, and he is now considered an established case. It has not yet been conclusively established that this was a laboratory infection, rather than due to community transmission. Laboratory transmission is the prevailing theory, however, and WHO has not expressed great concern that this patient represents the beginning of a new SARS season. No transmission from this patient has occurred; thus, things remain quiet in terms of clinical disease. Two planning meetings have been held at CDC, involving representatives of relevant professional organizations. In addition, a story in the Wall Street Journal (Sept. 23, 2003) highlighted a glimpse at CDC’s yet to be released SARS Preparedness Plan. The first of two telecasts from CDC on its Public Health Training Network also provided more insight into the directions the new CDC recommendations will take. This telecast featured presentations on infection control issues, quarantine and community response issues, and legal issues. The second of the two telecasts was held on Sept. 30, and presented clinical information on SARS diagnosis and management, laboratory diagnosis, and surveillance with the goal of early recognition. Meanwhile, expect that many, if not most of the SARS recommendations posted on the CDC Web site earlier this year will be revised based on information gained from analysis of last year’s experiences. In the Sept. 23 telecast, Linda Chiarello, RN, MS, a CDC epidemiologist, led off with a presentation on infection control issues. She derived her major points from lessons learned in the Toronto experiences, citing three actual scenarios. The first took place in the emergency department (ED) of one of the hospitals, in which the wife of a possible SARS patient seen there remained in the waiting room for several hours before her husband was eventually admitted. The wife herself was incubating SARS, was already febrile and transmitted SARS to 13 additional people in the waiting area, including a few health care workers (HCWs). The recommendation that emerged from this experience was to focus on “source control,” to give greater attention to masking everyone with fever and respiratory symptoms that comes in the door, whether the person to be seen is in the ED or accompanying people. In addition, consideration should be given to creating a separate waiting area for those who needed to be masked, as a further protection against transmission within the ED setting. The same issues and the same potential solutions should apply in primary care clinics and physicians' offices. Precautions must be applied in triage, reception and waiting areas. The second illustrative scenario occurred in a hospital where, after the outbreak was believed to be over, cases in HCWs began to occur again about a week after barrier precautions were relaxed. Two lessons emerged from this experience:
The third scenario illustrated the high risk of transmission during aerosol-generating procedures. In this widely publicized incident, SARS was transmitted to 11 HCWs who provided care to a SARS patient (a family practice physician) around the time of intubation. He was in severe respiratory distress, with large quantities of frothy sputum and respiratory secretions. This episode was one of several that led both WHO and CDC to recommend consideration of using PAPRs (Powered Air Purifying Respirators), instead of N-95 masks during invasive or cough-generating respiratory procedures such as intubation. One startling statistic emerged from Ms. Chiarello’s discussion; in Toronto, 65% of SARS cases occurred in HCWs! Thus, anticipate that there may be widespread reluctance to care for SARS patients among HCWs, and some may opt to “walk,” although this evidently did not happen to an appreciable extent in Toronto. A variety of related infection control issues were discussed. These include consideration of the hospital organizational infrastructure, segregation of suspect from probable patients, and segregation of both from other patients, possible creation and configuration of dedicated SARS units, traffic control, visitor limitation, personnel training, and the like. A surveillance mechanism needs to be established to recognize SARS signs and symptoms not only in patients, but in HCWs as well. Crucial details of SARS transmission are yet to be established with confidence. The CDC continues to believe, as do I and most ID physicians, that most SARS transmission is by droplets, but barrier precautions become vastly more complicated as a result of our uncertainty about the roles, if any, of fomites and the airborne route. The nature of “super-spreaders” is still poorly understood. The other presentations on quarantine and community issues and legal considerations were of great interest, but less relevant to immediate hospital preparedness planning. The fundamental underlying question remains: “If SARS comes back, how will we know it?” If we experience a significant outbreak of influenza A/H3N2, as many of us expect, it promises to be a memorable respiratory disease season! For more information: |
