Individual Correlates of Infectivity of Influenza A Virus Infections in Households

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. In a detailed study of influenza virus transmission within househo...

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Bibliographic Details
Published in:PloS one 2016-05, Vol.11 (5), p.e0154418-e0154418
Main Authors: Tsang, Tim K, Fang, Vicky J, Chan, Kwok-Hung, Ip, Dennis K M, Leung, Gabriel M, Peiris, J S Malik, Cowling, Benjamin J, Cauchemez, Simon
Format: Article
Language:English
Subjects:
Adolescent
Adult
Biology and Life Sciences
Disease control
Epidemiology
Family Characteristics
Female
Hong Kong
Households
Housing and health
Humans
Illnesses
Infections
Infectious diseases
Infectivity
Influenza
Influenza A
Influenza A virus
Influenza A virus - pathogenicity
Influenza research
Influenza, Human - virology
Laboratories
Male
Medicine
Medicine and Health Sciences
Middle Aged
Nose
Pandemics
Pharynx
Polymerase chain reaction
Public health
Statistical analysis
Studies
Swine flu
Trends
Virulence
Virus Shedding
Viruses
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Summary: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. 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. 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. 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.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0154418