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Article: Assessing asymptomatic, pre-symptomatic and symptomatic transmission risk of SARS-CoV-2

TitleAssessing asymptomatic, pre-symptomatic and symptomatic transmission risk of SARS-CoV-2
Authors
KeywordsSARS-CoV-2
COVID-19
asymptomatic
pre-symptomatic
symptomatic
Issue Date2021
PublisherOxford University Press. The Journal's web site is located at http://www.oxfordjournals.org/our_journals/cid/
Citation
Clinical Infectious Diseases, 2021, Epub 2021-03-27 How to Cite?
AbstractBackground: The relative contributions of asymptomatic, pre-symptomatic and symptomatic transmission of SARS-CoV-2 have not been clearly measured although control measures may differ in response to the risk of spread posed by different types of cases. Methods: We collected detailed information on transmission events and symptom status based on laboratory-confirmed patient data and contact tracing data from four provinces and one municipality in China. We estimated the variation in risk of transmission over time, and the severity of secondary infections, by symptomatic status of the infector. Results: There were 393 symptomatic index cases with 3136 close contacts and 185 asymptomatic index cases with 1078 close contacts included into the study. The secondary attack rate among close contacts of symptomatic and asymptomatic index cases were 4.1% (128/3136) and 1.1% (12/1078), respectively, corresponding to a higher transmission risk from symptomatic cases than from asymptomatic cases (OR: 3.79, 95% CI: 2.06, 6.95). Approximately 25% (32/128) and 50% (6/12) of the infected close contacts were asymptomatic from symptomatic and asymptomatic index cases, respectively, while more than one third (38%) of the infections in the close contacts of symptomatic cases were attributable to exposure to the index cases before symptom onset. Infected contacts of asymptomatic index cases were more likely to be asymptomatic and less likely to be severe. Conclusions: Asymptomatic and pre-symptomatic transmission play an important role in spreading infection, although asymptomatic cases pose a lower risk of transmission than symptomatic cases. Early case detection and effective test-and-trace measures are important to reduce transmission.
DescriptionBronze open access
Persistent Identifierhttp://hdl.handle.net/10722/298661
ISSN
2020 Impact Factor: 9.079
2020 SCImago Journal Rankings: 3.440
PubMed Central ID

 

DC FieldValueLanguage
dc.contributor.authorWu, P-
dc.contributor.authorLiu, F-
dc.contributor.authorChang, Z-
dc.contributor.authorLin, Y-
dc.contributor.authorRen, M-
dc.contributor.authorZheng, C-
dc.contributor.authorLi, Y-
dc.contributor.authorPeng, Z-
dc.contributor.authorQin, Y-
dc.contributor.authorYu, J-
dc.contributor.authorGeng, M-
dc.contributor.authorYang, X-
dc.contributor.authorZhao, H-
dc.contributor.authorLi, Z-
dc.contributor.authorZhou, S-
dc.contributor.authorRan, L-
dc.contributor.authorCowling, BJ-
dc.contributor.authorLai, S-
dc.contributor.authorChen, Q-
dc.contributor.authorWang, L-
dc.contributor.authorTsang, TK-
dc.contributor.authorLi, Z-
dc.date.accessioned2021-04-12T03:01:38Z-
dc.date.available2021-04-12T03:01:38Z-
dc.date.issued2021-
dc.identifier.citationClinical Infectious Diseases, 2021, Epub 2021-03-27-
dc.identifier.issn1058-4838-
dc.identifier.urihttp://hdl.handle.net/10722/298661-
dc.descriptionBronze open access-
dc.description.abstractBackground: The relative contributions of asymptomatic, pre-symptomatic and symptomatic transmission of SARS-CoV-2 have not been clearly measured although control measures may differ in response to the risk of spread posed by different types of cases. Methods: We collected detailed information on transmission events and symptom status based on laboratory-confirmed patient data and contact tracing data from four provinces and one municipality in China. We estimated the variation in risk of transmission over time, and the severity of secondary infections, by symptomatic status of the infector. Results: There were 393 symptomatic index cases with 3136 close contacts and 185 asymptomatic index cases with 1078 close contacts included into the study. The secondary attack rate among close contacts of symptomatic and asymptomatic index cases were 4.1% (128/3136) and 1.1% (12/1078), respectively, corresponding to a higher transmission risk from symptomatic cases than from asymptomatic cases (OR: 3.79, 95% CI: 2.06, 6.95). Approximately 25% (32/128) and 50% (6/12) of the infected close contacts were asymptomatic from symptomatic and asymptomatic index cases, respectively, while more than one third (38%) of the infections in the close contacts of symptomatic cases were attributable to exposure to the index cases before symptom onset. Infected contacts of asymptomatic index cases were more likely to be asymptomatic and less likely to be severe. Conclusions: Asymptomatic and pre-symptomatic transmission play an important role in spreading infection, although asymptomatic cases pose a lower risk of transmission than symptomatic cases. Early case detection and effective test-and-trace measures are important to reduce transmission.-
dc.languageeng-
dc.publisherOxford University Press. The Journal's web site is located at http://www.oxfordjournals.org/our_journals/cid/-
dc.relation.ispartofClinical Infectious Diseases-
dc.rightsPost-print: This is a pre-copy-editing, author-produced PDF of an article accepted for publication in [insert journal title] following peer review. The definitive publisher-authenticated version [insert complete citation information here] is available online at: xxxxxxx [insert URL that the author will receive upon publication here]. -
dc.subjectSARS-CoV-2-
dc.subjectCOVID-19-
dc.subjectasymptomatic-
dc.subjectpre-symptomatic-
dc.subjectsymptomatic-
dc.titleAssessing asymptomatic, pre-symptomatic and symptomatic transmission risk of SARS-CoV-2-
dc.typeArticle-
dc.identifier.emailWu, P: pengwu@hku.hk-
dc.identifier.emailLin, Y: vanialin@HKUCC-COM.hku.hk-
dc.identifier.emailCowling, BJ: bcowling@hku.hk-
dc.identifier.emailTsang, TK: matklab@hku.hk-
dc.identifier.authorityWu, P=rp02025-
dc.identifier.authorityCowling, BJ=rp01326-
dc.identifier.authorityTsang, TK=rp02571-
dc.description.naturelink_to_OA_fulltext-
dc.identifier.doi10.1093/cid/ciab271-
dc.identifier.pmid33772573-
dc.identifier.pmcidPMC8083716-
dc.identifier.hkuros322128-
dc.identifier.volumeEpub 2021-03-27-
dc.publisher.placeUnited States-

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