Individual Correlates of Infectivity of Influenza A Virus Infections in Households.

<h4>Background</h4>Identifying individual correlates of infectivity of influenza virus is important for disease control and prevention. Viral shedding is used as a proxy measure of infectivity in many studies. However, the evidence for this is limited.<h4>Methods</h4>In a det...

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Main Authors: Tim K Tsang, Vicky J Fang, Kwok-Hung Chan, Dennis K M Ip, Gabriel M Leung, J S Malik Peiris, Benjamin J Cowling, Simon Cauchemez
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2016-01-01
Series:PLoS ONE
Online Access:https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0154418&type=printable
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author Tim K Tsang
Vicky J Fang
Kwok-Hung Chan
Dennis K M Ip
Gabriel M Leung
J S Malik Peiris
Benjamin J Cowling
Simon Cauchemez
author_facet Tim K Tsang
Vicky J Fang
Kwok-Hung Chan
Dennis K M Ip
Gabriel M Leung
J S Malik Peiris
Benjamin J Cowling
Simon Cauchemez
author_sort Tim K Tsang
collection DOAJ
description <h4>Background</h4>Identifying individual correlates of infectivity of influenza virus is important for disease control and prevention. Viral shedding is used as a proxy measure of infectivity in many studies. However, the evidence for this is limited.<h4>Methods</h4>In a detailed study of influenza virus transmission within households in 2008-12, we recruited index cases with confirmed influenza infection from outpatient clinics, and followed up their household contacts for 7-10 days to identify secondary infections. We used individual-based hazard models to characterize the relationship between individual viral shedding and individual infectivity.<h4>Results</h4>We analyzed 386 households with 1147 household contacts. Index cases were separated into 3 groups according to their estimated level of viral shedding at symptom onset. We did not find a statistically significant association of virus shedding with transmission. Index cases in medium and higher viral shedding groups were estimated to have 21% (95% CI: -29%, 113%) and 44% (CI: -16%, 167%) higher infectivity, compared with those in the lower viral shedding group.<h4>Conclusions</h4>Individual viral load measured by RT-PCR in the nose and throat was at most weakly correlated with individual infectivity in households. Other correlates of infectivity should be examined in future studies.
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spelling doaj-art-a3a26a8c19734927aaee6deb5d2db61a2025-08-20T02:31:58ZengPublic Library of Science (PLoS)PLoS ONE1932-62032016-01-01115e015441810.1371/journal.pone.0154418Individual Correlates of Infectivity of Influenza A Virus Infections in Households.Tim K TsangVicky J FangKwok-Hung ChanDennis K M IpGabriel M LeungJ S Malik PeirisBenjamin J CowlingSimon Cauchemez<h4>Background</h4>Identifying individual correlates of infectivity of influenza virus is important for disease control and prevention. Viral shedding is used as a proxy measure of infectivity in many studies. However, the evidence for this is limited.<h4>Methods</h4>In a detailed study of influenza virus transmission within households in 2008-12, we recruited index cases with confirmed influenza infection from outpatient clinics, and followed up their household contacts for 7-10 days to identify secondary infections. We used individual-based hazard models to characterize the relationship between individual viral shedding and individual infectivity.<h4>Results</h4>We analyzed 386 households with 1147 household contacts. Index cases were separated into 3 groups according to their estimated level of viral shedding at symptom onset. We did not find a statistically significant association of virus shedding with transmission. Index cases in medium and higher viral shedding groups were estimated to have 21% (95% CI: -29%, 113%) and 44% (CI: -16%, 167%) higher infectivity, compared with those in the lower viral shedding group.<h4>Conclusions</h4>Individual viral load measured by RT-PCR in the nose and throat was at most weakly correlated with individual infectivity in households. Other correlates of infectivity should be examined in future studies.https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0154418&type=printable
spellingShingle Tim K Tsang
Vicky J Fang
Kwok-Hung Chan
Dennis K M Ip
Gabriel M Leung
J S Malik Peiris
Benjamin J Cowling
Simon Cauchemez
Individual Correlates of Infectivity of Influenza A Virus Infections in Households.
PLoS ONE
title Individual Correlates of Infectivity of Influenza A Virus Infections in Households.
title_full Individual Correlates of Infectivity of Influenza A Virus Infections in Households.
title_fullStr Individual Correlates of Infectivity of Influenza A Virus Infections in Households.
title_full_unstemmed Individual Correlates of Infectivity of Influenza A Virus Infections in Households.
title_short Individual Correlates of Infectivity of Influenza A Virus Infections in Households.
title_sort individual correlates of infectivity of influenza a virus infections in households
url https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0154418&type=printable
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