Superspreading SARS Events, Beijing, 2003

Abstract

Superspreading events were pivotal in the global spread of severe acute respiratory syndrome (SARS). We investigated superspreading in one transmission chain early in Beijing’s epidemic. Superspreading was defined as transmission of SARS to at least eight contacts. An index patient with onset of SARS 2 months after hospital admission was the source of four generations of transmission to 76 case-patients, including 12 healthcare workers and several hospital visitors. Four (5%) case circumstances met the superspreading definition. Superspreading appeared to be associated with older age (mean 56 vs. 44 years), case fatality (75% vs. 16%, p = 0.02, Fisher exact test), number of close contacts (36 vs. 0.37) and attack rate among close contacts (43% vs. 18.5%, p < 0.025). Delayed recognition of SARS in a hospitalized patient permitted transmission to patients, visitors, and healthcare workers. Older age and number of contacts merit investigation in future studies of superspreading.

Severe Acute Respiratory Syndrome (SARS): A Year in Review

“…Infected individuals have on occasion generated a disproportionately large number of transmissions, and the relative contributions of agent, host, and environmental factors to these so-called "superspreading" events require further study (3,(31)(32)(33). It is not known whether some virus lineages are more prone to transmission than others.…”

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“…From our findings, it appears that the difference between success and failure for SARS is the presence or absence of high-ν individuals in the early generations of the outbreak. This important role for superspreaders has been suggested before for several directly-transmitted diseases [44,77,42], and is easily and intuitively included in modeling analyses using a continuously distributed Extinction probability from NB pgf Extinction probability from empirical pgf Figure 5. Extinction probabilities generated using empirical and negative binomial (NB) probability generating functions (pgf's).…”

“…Such was the case during the global emergence of severe acute respiratory syndrome (SARS) in 2003, when numerous 'superspreading events' (SSEs) were reported in which certain individuals infected large numbers of secondary cases [54,77]. These individuals did not share obvious attributes that would have allowed them to be identified in advance as potential superspreaders, particularly given the broad spectrum of symptoms exhibited by SARS patients [72].…”

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“…On 27 June 2013, WHO revised their 'Interim surveillance recommendations for human infection with Middle East respiratory syndrome coronavirus' [33]; the update strongly recommends that specimens should be collected both from the upper and lower respiratory tract (see laboratory section). Clinicians should be familiar with the most recent WHO surveillance guidance [36], case investigation guidelines [37], WHO case definitions for MERS-CoV [34] and infection control guidelines, all of which can be found on the WHO Global Alert and Response webpage for coronavirus.…”