Clinical management of severe acute respiratory infection ...
Severe acute respiratory syndrome: Did quarantine help?downloads.hindawi.com › journals › cjidmm...
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Can J Infect Dis Med Microbiol Vol 15 No 4 July/August 2004 204 Severe acute respiratory syndrome: Did quarantine help? Richard Schabas MD MHSc FRCPC York Central Hospital, Richmond Hill, Ontario Correspondence and reprints: Dr Richard Schabas, York Central Hospital, 10 Trench Street, Richmond Hill, Ontario, L4C 4Z3. Telephone 905-883-1212 ext 312, fax 905-883-2455, e-mail [email protected] Q uarantine, the isolation of asymptomatic individuals who are thought to be incubating infection, was a prominent control strategy used in the recent severe acute respiratory syn- drome (SARS) outbreaks. A recent report about the public health efforts to control SARS in Toronto concluded that in future outbreaks “for every case of SARS, health authorities should expect to quarantine up to 100 contacts” (1). This is a remarkable conclusion. It is one thing to resort to an unproven intervention in the crisis posed by a novel disease threat; however, it is quite another to recommend the contin- ued use of this intervention after the dust has settled and we know, or should know, a great deal more about the problem at hand. Mass quarantine for disease control was essentially aban- doned last century. Does it deserve a second look? An outbreak should meet the following three criteria for quarantine to be a useful measure of disease control: • first, people likely to be incubating the infection must be efficiently and effectively identified; • second, those people must comply with the conditions of quarantine, and; • third, the infectious disease in question must be transmissible in its presymptomatic or early symptomatic stages. The use of quarantine in the Toronto outbreak failed on all three counts. SARS quarantine in Toronto was both inefficient and inef- fective. It was massive in scale. Toronto public health authori- ties quarantined approximately 100 people for each SARS case, while Beijing public health quarantined about 12 people for each SARS case. An analysis of the efficiency of quaran- tine in the Beijing outbreak conducted by the American Centers for Disease Control and Prevention concluded that quarantine could have been reduced by two-thirds, (four peo- ple per SARS case) without compromising effectiveness if authorities had “focused only on persons who had contact with an actively ill SARS patient” (2). This analysis suggests that Toronto quarantined at least 25 times more people than was appropriate. Concerns about this inefficiency were raised quite early in the outbreak (3,4). The Toronto quarantine was clearly ineffective in identify- ing potential SARS patients. At least the first 50 cases in the second phase of the outbreak were not quarantined. Compliance with the Toronto quarantine was poor. Only 57% (13,291 of 23,103) of people quarantined were ‘compliant’, according to Toronto officials (1), although how this was defined and measured is not clear. It is hard to understand how anyone could attribute the rapid and effective elimination of an infectious disease to an intervention with such low compliance. We now know a great deal more about the natural history of SARS and its transmission. In fact, the evidence is compelling and shows that SARS is not infectious during the preclinical phase and does not become significantly infectious until the symptomatic illness is well-established. Peak infectivity is in the second week of clinical illness (5). If ever an infectious dis- ease was ill-suited for quarantine, it is SARS. Did quarantine work for SARS? Notwithstanding the con- clusions of the Toronto public health group, I think the evi- dence is now overwhelming that quarantine played little or no role in controlling SARS. Furthermore, mass quarantine, as practiced in Toronto, did considerable harm by sapping public health resources and fueling public anxiety. SARS was rapidly controlled and eradicated in Toronto and everywhere else that it appeared. Fundamentally, this is because SARS is only capable of sustained transmission in hos- pitals that do not suspect its presence. SARS is not capable of sustained transmission in the community (6). Case identifica- tion and isolation in hospitals is what controlled SARS. Quarantine, as such, played no role. In the unlikely event of another SARS outbreak in Canada, public health officials should quarantine no one. Instead, they should identify and observe close contacts of cases, ie, people with a ‘reasonable suspicion’ of SARS. These close contacts should be isolated if, and only if, they develop symp- toms consistent with the current recommendations of the World Health Organization (5). ©2004 Pulsus Group Inc. All rights reserved COMMENTARY REFERENCES 1. Svoboda T, Henry B, Shulman L, et al. Public health measures to control the spread of severe acute respiratory syndrome during the outbreak in Toronto. N Engl J Med 2004;350:2352-61. 2. Efficiency of quarantine during an epidemic of severe acute respiratory syndrome – Beijing, China. MMWR Morb Mortal Wkly Rep 2003;52:1037-40. 3. Dwosh H, Hong H, Austgarden D, Herman S, Schabas R. Identification and containment of an outbreak of SARS in a community hospital. CMAJ 2003;168:1415-20. 4. Schabas R. SARS: Prudence, not panic. CMAJ 2003;168:1432-4. 5. World Health Organization. Consensus document on the epidemiology of severe acute respiratory syndrome (SARS). WHO/CDS/CSR/GAR/ 2003;11:4, 8-10. <www.who.int/csr/sars/en/WHOconsensus.pdf> (Version current at July 22, 2004). 6. Low D. Why SARS will not return: A polemic. CMAJ 2004;170:68-9.
Transcript of Severe acute respiratory syndrome: Did quarantine help?downloads.hindawi.com › journals › cjidmm...
Can J Infect Dis Med Microbiol Vol 15 No 4 July/August 2004204
Severe acute respiratory syndrome:Did quarantine help?
Richard Schabas MD MHSc FRCPC
York Central Hospital, Richmond Hill, OntarioCorrespondence and reprints: Dr Richard Schabas, York Central Hospital, 10 Trench Street, Richmond Hill, Ontario, L4C 4Z3.
Telephone 905-883-1212 ext 312, fax 905-883-2455, e-mail [email protected]
Quarantine, the isolation of asymptomatic individuals whoare thought to be incubating infection, was a prominent
control strategy used in the recent severe acute respiratory syn-drome (SARS) outbreaks. A recent report about the publichealth efforts to control SARS in Toronto concluded that infuture outbreaks “for every case of SARS, health authoritiesshould expect to quarantine up to 100 contacts” (1).
This is a remarkable conclusion. It is one thing to resort toan unproven intervention in the crisis posed by a novel diseasethreat; however, it is quite another to recommend the contin-ued use of this intervention after the dust has settled and weknow, or should know, a great deal more about the problem athand. Mass quarantine for disease control was essentially aban-doned last century. Does it deserve a second look?
An outbreak should meet the following three criteria forquarantine to be a useful measure of disease control:
• first, people likely to be incubating the infection must
be efficiently and effectively identified;
• second, those people must comply with the conditions
of quarantine, and;
• third, the infectious disease in question must be
transmissible in its presymptomatic or early
symptomatic stages.
The use of quarantine in the Toronto outbreak failed on allthree counts.
SARS quarantine in Toronto was both inefficient and inef-fective. It was massive in scale. Toronto public health authori-ties quarantined approximately 100 people for each SARScase, while Beijing public health quarantined about 12 peoplefor each SARS case. An analysis of the efficiency of quaran-tine in the Beijing outbreak conducted by the AmericanCenters for Disease Control and Prevention concluded thatquarantine could have been reduced by two-thirds, (four peo-ple per SARS case) without compromising effectiveness ifauthorities had “focused only on persons who had contact withan actively ill SARS patient” (2).
This analysis suggests that Toronto quarantined at least25 times more people than was appropriate. Concerns aboutthis inefficiency were raised quite early in the outbreak (3,4).
The Toronto quarantine was clearly ineffective in identify-ing potential SARS patients. At least the first 50 cases in thesecond phase of the outbreak were not quarantined.
Compliance with the Toronto quarantine was poor. Only57% (13,291 of 23,103) of people quarantined were ‘compliant’,according to Toronto officials (1), although how this was
defined and measured is not clear. It is hard to understandhow anyone could attribute the rapid and effective eliminationof an infectious disease to an intervention with such lowcompliance.
We now know a great deal more about the natural history ofSARS and its transmission. In fact, the evidence is compellingand shows that SARS is not infectious during the preclinicalphase and does not become significantly infectious until thesymptomatic illness is well-established. Peak infectivity is inthe second week of clinical illness (5). If ever an infectious dis-ease was ill-suited for quarantine, it is SARS.
Did quarantine work for SARS? Notwithstanding the con-clusions of the Toronto public health group, I think the evi-dence is now overwhelming that quarantine played little or norole in controlling SARS. Furthermore, mass quarantine, aspracticed in Toronto, did considerable harm by sapping publichealth resources and fueling public anxiety.
SARS was rapidly controlled and eradicated in Toronto andeverywhere else that it appeared. Fundamentally, this isbecause SARS is only capable of sustained transmission in hos-pitals that do not suspect its presence. SARS is not capable ofsustained transmission in the community (6). Case identifica-tion and isolation in hospitals is what controlled SARS.Quarantine, as such, played no role.
In the unlikely event of another SARS outbreak inCanada, public health officials should quarantine no one.Instead, they should identify and observe close contacts of cases,ie, people with a ‘reasonable suspicion’ of SARS. These closecontacts should be isolated if, and only if, they develop symp-toms consistent with the current recommendations of theWorld Health Organization (5).
©2004 Pulsus Group Inc. All rights reserved
COMMENTARY
REFERENCES
1. Svoboda T, Henry B, Shulman L, et al. Public health measures tocontrol the spread of severe acute respiratory syndrome during theoutbreak in Toronto. N Engl J Med 2004;350:2352-61.
2. Efficiency of quarantine during an epidemic of severe acuterespiratory syndrome – Beijing, China. MMWR Morb MortalWkly Rep 2003;52:1037-40.
3. Dwosh H, Hong H, Austgarden D, Herman S, Schabas R.Identification and containment of an outbreak of SARS in acommunity hospital. CMAJ 2003;168:1415-20.
4. Schabas R. SARS: Prudence, not panic. CMAJ 2003;168:1432-4.5. World Health Organization. Consensus document on the
epidemiology of severe acute respiratory syndrome (SARS).WHO/CDS/CSR/GAR/ 2003;11:4, 8-10.<www.who.int/csr/sars/en/WHOconsensus.pdf> (Version current atJuly 22, 2004).
6. Low D. Why SARS will not return: A polemic. CMAJ2004;170:68-9.
Schabas.qxd 8/6/2004 2:49 PM Page 204
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