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Article: The Fraction of Influenza Virus Infections That Are Asymptomatic: A Systematic Review and Meta-analysis

TitleThe Fraction of Influenza Virus Infections That Are Asymptomatic: A Systematic Review and Meta-analysis
Authors
Issue Date2015
PublisherLippincott Williams & Wilkins. The Journal's web site is located at http://www.epidem.com
Citation
Epidemiology, 2015, v. 26 n. 6, p. 862-872 How to Cite?
AbstractBACKGROUND: The fraction of persons with influenza virus infection, who do not report any signs or symptoms throughout the course of infection is referred to as the asymptomatic fraction. METHODS: We conducted a systematic review and meta-analysis of published estimates of the asymptomatic fraction of influenza virus infections. We found that estimates of the asymptomatic fraction were reported from two different types of studies: first, outbreak investigations with short-term follow-up of potentially exposed persons and virologic confirmation of infections; second, studies conducted across epidemics typically evaluating rates of acute respiratory illness among persons with serologic evidence of infection, in some cases adjusting for background rates of illness from other causes. RESULTS: Most point estimates from studies of outbreak investigations fell in the range 4%-28% with low heterogeneity (I = 0%) with a pooled mean of 16% (95% confidence interval = 13%, 19%). Estimates from the studies conducted across epidemics without adjustment were very heterogeneous (point estimates 0%-100%; I = 97%), while estimates from studies that adjusted for background illnesses were more consistent with point estimates in the range 65%-85% and moderate heterogeneity (I = 58%). Variation in estimates could be partially explained by differences in study design and analysis, and inclusion of mild symptomatic illnesses as asymptomatic in some studies. CONCLUSIONS: Estimates of the asymptomatic fraction are affected by the study design, and the definitions of infection and symptomatic illness. Considerable differences between the asymptomatic fraction of infections confirmed by virologic versus serologic testing may indicate fundamental differences in the interpretation of these two indicators.
Persistent Identifierhttp://hdl.handle.net/10722/211643
ISSN
2015 Impact Factor: 6.075
2015 SCImago Journal Rankings: 2.981
PubMed Central ID

 

DC FieldValueLanguage
dc.contributor.authorLeung, NHL-
dc.contributor.authorXu, C-
dc.contributor.authorIp, DKM-
dc.contributor.authorCowling, BJ-
dc.date.accessioned2015-07-21T02:06:31Z-
dc.date.available2015-07-21T02:06:31Z-
dc.date.issued2015-
dc.identifier.citationEpidemiology, 2015, v. 26 n. 6, p. 862-872-
dc.identifier.issn1044-3983-
dc.identifier.urihttp://hdl.handle.net/10722/211643-
dc.description.abstractBACKGROUND: The fraction of persons with influenza virus infection, who do not report any signs or symptoms throughout the course of infection is referred to as the asymptomatic fraction. METHODS: We conducted a systematic review and meta-analysis of published estimates of the asymptomatic fraction of influenza virus infections. We found that estimates of the asymptomatic fraction were reported from two different types of studies: first, outbreak investigations with short-term follow-up of potentially exposed persons and virologic confirmation of infections; second, studies conducted across epidemics typically evaluating rates of acute respiratory illness among persons with serologic evidence of infection, in some cases adjusting for background rates of illness from other causes. RESULTS: Most point estimates from studies of outbreak investigations fell in the range 4%-28% with low heterogeneity (I = 0%) with a pooled mean of 16% (95% confidence interval = 13%, 19%). Estimates from the studies conducted across epidemics without adjustment were very heterogeneous (point estimates 0%-100%; I = 97%), while estimates from studies that adjusted for background illnesses were more consistent with point estimates in the range 65%-85% and moderate heterogeneity (I = 58%). Variation in estimates could be partially explained by differences in study design and analysis, and inclusion of mild symptomatic illnesses as asymptomatic in some studies. CONCLUSIONS: Estimates of the asymptomatic fraction are affected by the study design, and the definitions of infection and symptomatic illness. Considerable differences between the asymptomatic fraction of infections confirmed by virologic versus serologic testing may indicate fundamental differences in the interpretation of these two indicators.-
dc.languageeng-
dc.publisherLippincott Williams & Wilkins. The Journal's web site is located at http://www.epidem.com-
dc.relation.ispartofEpidemiology-
dc.rightsThis is a non-final version of an article published in final form in Epidemiology, 2015, v. 26 n. 6, p. 862-872-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.titleThe Fraction of Influenza Virus Infections That Are Asymptomatic: A Systematic Review and Meta-analysis-
dc.typeArticle-
dc.identifier.emailXu, C: xuceline@hku.hk-
dc.identifier.emailIp, DKM: dkmip@hku.hk-
dc.identifier.emailCowling, BJ: bcowling@hku.hk-
dc.identifier.authorityIp, DKM=rp00256-
dc.identifier.authorityCowling, BJ=rp01326-
dc.description.naturepostprint-
dc.identifier.doi10.1097/EDE.0000000000000340-
dc.identifier.pmid26133025-
dc.identifier.pmcidPMC4586318-
dc.identifier.hkuros245574-
dc.identifier.volume26-
dc.identifier.issue6-
dc.identifier.spage862-
dc.identifier.epage872-
dc.publisher.placeUnited States-

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