Risk Factors for SARS among Persons without Known Contact with SARS Patients, Beijing, China

Abstract

Most cases of severe acute respiratory syndrome (SARS) have occurred in close contacts of SARS patients. However, in Beijing, a large proportion of SARS cases occurred in persons without such contact. We conducted a case-control study in Beijing that compared exposures of 94 unlinked, probable SARS patients with those of 281 community-based controls matched for age group and sex. Case-patients were more likely than controls to have chronic medical conditions or to have visited fever clinics (clinics at which possible SARS patients were separated from other patients), eaten outside the home, or taken taxis frequently. The use of masks was strongly protective. Among 31 case-patients for whom convalescent-phase (>21 days) sera were available, 26% had immunoglobulin G to SARS-associated coronavirus. Our finding that clinical SARS was associated with visits to fever clinics supports Beijing’s strategy of closing clinics with poor infection-control measures. Our finding that mask use lowered the risk for disease supports the community’s use of this strategy.

Prevention of nosocomial transmission of swine-origin pandemic influenza virus A/H1N1 by infection control bundle

“…According to our analysis, use of surgical masks by the exposed persons was associated with a lower risk of nosocomial acquisition of S-OIV, which was consistent with previous studies suggesting that wearing a surgical mask might decrease the risk of SARS infection. 7 This measure discouraged the use of fingers to touch the mucous membranes of the nostrils and mouth since such spontaneous behaviour was not infrequently observed. 8 Wearing surgical masks by the index persons as a form of source control also reduced the risk of transmission.…”

SARS-coronavirus (SARS-CoV) and the safety of a solvent/detergent (S/D) treated immunoglobulin preparation

“…Although human-to-human transmission of SARS-CoV is less efficient than for other air-borne viruses such as influenza A viruses, the recent SARS epidemic was characterised by several explosive outbreaks [4,24]. Most infections resulted from direct transmission via respiratory droplets during close personal contact and adequate protective measures were shown to be effective [22,25]. However, there are a number of instances when transmission occurred through other modes not yet well defined.…”

Effectiveness of hand hygiene and provision of information in preventing influenza cases requiring hospitalization

“…A case-control study in Hong Kong (Lau et al, 2004) found a very similar effectiveness of handwashing >10 times a day in the community in preventing the transmission of SARS (OR = 0.58). Another case-control study in Beijing (Wu et al, 2004) found that handwashing after returning home had a protective effect (OR = 0.3). More recently, a meta-analysis of 6 casecontrol studies (Jefferson et al, 2008), found that handwashing > 10 times daily was remarkably effective in preventing SARS (OR = 0.45, CI 0.36-0.57).…”