secondary attack rate and superspreading events for sars cov 2 CORD-Papers-2022-06-02 (Version 1)

Title: Secondary attack rate and superspreading events for SARS-CoV-2
Published: 2020-02-27
Journal: Lancet
DOI: 10.1016/s0140-6736(20)30462-1
Author Name: Liu Yang
Author link:
Author Name: Eggo Rosalind M
Author link:
Author Name: Kucharski Adam J
Author link:
license: no-cc
license_url: [no creative commons license associated]
source_x: Elsevier; Medline; PMC
pubmed_id: 32113505
pmcid: PMC7158947
has_full_text: TRUE
Keywords Extracted from PMC Text: R0=SARHNH+ SARCNC Wuhan SARS-CoV-2 people coronavirus 2 respectively.3 between-household
Extracted PMC Text Content in Record: First 5000 Characters:A basic reproduction number, R0, of about 2 was estimated for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Wuhan, China, early in the outbreak.1, 2 However, this value only captures the average dynamics of transmission; a crucial question for control is whether specific situations and settings might be driving the outbreak. The secondary attack rate (SAR), defined as the probability that an infection occurs among susceptible people within a specific group (ie, household or close contacts), can provide an indication of how social interactions relate to transmission risk. Increasingly, outbreak investigations are providing insights into the risk of transmission in different settings. Drawing on data from nine recent reports of secondary transmission associated with a specific event such as a meal or holiday visit (table ), we estimated 48 secondary infections occurred among 137 attendees. Assuming that all these secondary infections were generated by a single primary case, which is probable given the short-term nature of the exposure events, would imply a SAR among close contacts of 35% (95% CI 27–44). If transmission is stratified by contacts within and outside of the household, the relationship between R0 and household risk is: R0=SARHNH+ SARCNC, where SARH and SARC are the secondary attack rates within household and wider community (ie, outside household), respectively, and NH and NC are the numbers of at-risk contacts made, respectively.3 An infection with a high household SAR but a modest R0 would therefore suggest transmission is driven by a relatively small number of high-risk contacts. A large household SAR further suggests that between-household transmission risk is lower; otherwise the observed R0 would be larger. More data are needed to reliably estimate the true within-household and between-household transmission for SARS-CoV-2; recent reports might be biased towards larger transmission events. However, if it transpires that most at-risk contacts have a close relationship with cases, and superspreading events tend to occur at large gatherings of these close contacts, measures to reduce infection risk during such gatherings and subsequent tracing of close contacts of cases might have a disproportionate effect on reducing overall transmission.
PMC JSON Files: document_parses/pmc_json/PMC7158947.xml.json
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