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Updated: Apr 24, 2026

Multi-target Parallel Processing Approach for Gene-to-structure Determination of the Influenza Polymerase PB2 Subunit
Published on: June 28, 2013
Influenza household transmission and genomic diversity in the United States: A prospective cohort study, 2022-2024
Sarah N Cox1, Julia C Bennett1, Amanda M Casto2
1University of Washington, Department of Medicine, 1959 NE Pacific Street, Seattle, WA 98195, USA; University of Washington, Department of Epidemiology, 3980 15th Ave NE, Seattle, WA 98195, USA.
Objectives:
To analyze the extent and risk factors of household influenza transmission using molecular testing and viral genomes.
Methods:
In a community-based cohort in the United States during 2022-2024, participants self-collected weekly nasal swabs. Swabs were tested for influenza by RT-PCR; genomic sequencing was performed. Index cases had the first influenza detection within households. Factors associated with household transmission were evaluated using Poisson regression.
Results:
Influenza transmission was detected in 56/303 influenza-positive households with a distinct index case. Most (82%) index cases were symptomatic; 16% of children vs 28% of adults were asymptomatic. 89/941 household contacts were infected 1-7 days after the index (secondary household infection risk: 9.5%, 95% CI: 7.3, 12.2). Index and secondary case median ages were 11 and 24 years, respectively. A greater proportion of contacts were infected when the index case was symptomatic (11%) vs asymptomatic (5%). Higher viral load was associated with 3.1 (1.7, 5.8) times higher risk of secondary infection. Most (13/16) index-secondary case pairs with available sequences differed by ≤3 nucleotides.
Conclusions:
Most household index cases were symptomatic children. Higher viral load and presence of symptoms among index cases were associated with household transmission. Home-based surveillance can assess household transmission using case chronology and genomics.
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