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Duration and distance of exposure are important predictors of transmission among community contacts of Ontario SARS cases

  • E. REA (a1) (a2), J. LAFLÈCHE (a1), S. STALKER (a3), B. K. GUARDA (a4), H. SHAPIRO (a5), I. JOHNSON (a2), S. J. BONDY (a2), R. UPSHUR (a2), M. L. RUSSELL (a6) and M. ELIASZIW (a6) (a7)...
Summary
SUMMARY

We report attack rates and contact-related predictors among community contacts of severe acute respiratory syndrome (SARS) cases from the 2003 Toronto-area outbreak. Community contact data was extracted from public health records for single, well-defined exposures to a SARS case. In total, 8662 community-acquired exposures resulted in 61 probable cases; a crude attack rate of 0·70% [95% confidence interval (CI) 0·54–0·90]. Persons aged 55–69 years were at higher risk of acquiring SARS (1·14%) than those either younger (0·60%) or older (0·70%). In multivariable analysis exposures for at least 30 min at a distance of ⩽1 m increased the likelihood of becoming a SARS case 20·4-fold (95% CI 11·8–35·1). Risk related to duration of illness in the source case at time of exposure was greatest for illness duration of 7–10 days (rate ratio 3·4, 95% CI 1·9–6·1). Longer and closer proximity exposures incurred the highest rate of disease. Separate measures of time and distance from source cases should be added to minimum datasets for the assessment of interventions for SARS and other emerging diseases.

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Corresponding author
*Author for correspondence: Dr M. Russell, Department of Community Health Sciences, 3330 Hospital Dr NW, Calgary, Alberta, CanadaT2N 4N1. (Email: mlrussel@ucalgary.ca)
References
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1. World Health Organization. Summary of probable SARS cases with onset of illness from 1 November 2002 to 31 July 2003 (http://www.who.int/csr/sars/country/table2004_04_21/en/print.html). Accessed 3 December 2005.
2. Public Health Agency of Canada. Canadian SARS numbers, September 3, 2003 (http://www.phac-aspc.gc.ca/sars-sras/cn-cc/20030903_e.html). Accessed 3 December 2005.
3. Ou J, et al. Efficiency of quarantine during an epidemic of severe acute respiratory syndrome: Beijing, China, 2003. Morbidity and Mortality Weekly Report 2003; 52: 10371040.
4. Svoboda T, et al. Public health measures to control the spread of the severe acute respiratory syndrome during the outbreak in Toronto. New England Journal of Medicine 2004; 350: 23522361.
5. Little RJA, Rubin DB. Statistical Aanalysis with Missing Data, 2nd edn. New York: Wiley, 2002.
6. SOLAS 3.0. Statistical Solutions Ltd, Saugus, MA, USA, 2001.
7. SAS 8.2. SAS Institute Inc., Cary, NC, USA, 2001.
8. Maldonado G, Greenland S. Simulation study of confounder-selection strategies. American Journal of Epidemiology 1993; 138: 923936.
9. Erdreich LS, Lee ET. Use of relative operating characteristic analysis in epidemiology. A method for dealing with subjective judgement. American Journal of Epidemiology 1981; 114: 649662.
10. Metz CE. ROC methodology in radiologic imaging. Investigative Radiology 1986; 21: 720733.
11. Nieto FJ, Coresh J. Adjusting survival curves for confounders: a review and a new method. American Journal of Epidemiology 1996; 143: 10591068.
12. Pang X, et al. Evaluation of control measures implemented in the Severe Acute Respiratory Syndrome outbreak in Beijing, 2003. Journal of the American Medical Association 2003; 290: 32153221.
13. Lee ML, et al. Use of quarantine to prevent transmission of Severe Acute Respiratory Syndrome – Taiwan, 2003. Morbidity and Mortality Weekly Report 2003; 52: 680683.
14. Goh DL, et al. Secondary household transmission of SARS, Singapore. Emerging Infectious Diseases 2004; 10: 232234.
15. Lau JTF, et al. Probable secondary infections in households of SARS patients in Hong Kong. Emerging Infectious Diseases 2004; 10: 235243.
16. Wilder-Smith A, et al. Asymptomatic SARS coronavirus infection among healthcare workers, Singapore. Emerging Infectious Diseases 2005; 11: 11421145.
17. Ip M, et al. Seroprevalence of antibody to severe acute respiratory Syndrome (SARS)-associated coronavirus among health care workers in SARS and non-SARS medical wards. Clinical Infectious Diseases 2003; 38: e116118.
18. Chow PK, et al. Healthcare worker seroconversion in SARS outbreak. Emerging Infectious Diseases 2004; 10: 249250.
19. Le DH, et al. Lack of SARS transmission among public hospital workers, Vietnam. Emerging Infectious Diseases 2004; 10: 265268.
20. Ho HT, et al. Colonization of severe acute respiratory syndrome-associated coronavirus among health-care workers screened by nasopharyngeal swab. Chest 2006; 129: 95101.
21. Lai TS, et al. Low prevalence of subclinical severe acute respiratory syndrome-associated coronavirus infection among hospital healthcare workers in Hong Kong. Scandinavian Journal of Infectious Diseases 2005; 37: 500503.
22. Scott RD, Gregg E, Meltzer MI. Collecting data to assess SARS interventions. Emerging Infectious Diseases 2004; 10: 12901292.
23. WHO. Global surveillance for severe acute respiratory syndrome (SARS). Weekly Epidemiological Record 2003; 78: 100110.
24. Wong TW, et al. Outbreak Study Group. Cluster of SARS among medical students exposed to single patient, Hong Kong. Emerging Infectious Diseases 2004; 10: 269276.
25. Centers for Disease Control and Prevention. Guidelines for the investigation of contacts of persons with infectious tuberculosis; recommendations from the National Tuberculosis Controllers Association and CDC. Morbidity and Mortality Weekly Report 2005; 54: 147.
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Epidemiology & Infection
  • ISSN: 0950-2688
  • EISSN: 1469-4409
  • URL: /core/journals/epidemiology-and-infection
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