tetano
Editor, Senior Moderator
J Infect
. 2026 Apr 20:106748.
doi: 10.1016/j.jinf.2026.106748. Online ahead of print.
INFLUENZA HOUSEHOLD TRANSMISSION AND GENOMIC DIVERSITY IN THE UNITED STATES: A PROSPECTIVE COHORT STUDY, 2022-2024
Sarah N Cox[SUP] 1 [/SUP], Julia C Bennett[SUP] 1 [/SUP], Amanda M Casto[SUP] 2 [/SUP], Katherine L Hoffman[SUP] 3 [/SUP], Collrane Frivold[SUP] 1 [/SUP], Marco Carone[SUP] 3 [/SUP], Zack Acker[SUP] 4 [/SUP], Tara M Babu[SUP] 2 [/SUP], Cassandra L Boisvert[SUP] 5 [/SUP], Brenna Ehmen[SUP] 4 [/SUP], Janet A Englund[SUP] 6 [/SUP], Sally Grindstaff[SUP] 4 [/SUP], Peter Han[SUP] 4 [/SUP], Tara L Hatchie[SUP] 2 [/SUP], Jennifer L Kuntz[SUP] 5 [/SUP], Christina M Lockwood[SUP] 7 [/SUP], Kathryn M McCaffrey[SUP] 4 [/SUP], Richard A Mularski[SUP] 5 [/SUP], Lani Regelbrugge[SUP] 4 [/SUP], Sacha Reich[SUP] 5 [/SUP], Mark A Schmidt[SUP] 5 [/SUP], Ning Smith[SUP] 5 [/SUP], Lea Starita[SUP] 8 [/SUP], Jeremy Stone[SUP] 4 [/SUP], Alexandra Varga[SUP] 5 [/SUP], Ana A Weil[SUP] 9 [/SUP], Allison L Naleway[SUP] 5 [/SUP], Helen Y Chu[SUP] 10 [/SUP]
Affiliations
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.
Keywords: adolescent; adult; community surveillance; epidemiology; genomics; household transmission; influenza; pediatric.
. 2026 Apr 20:106748.
doi: 10.1016/j.jinf.2026.106748. Online ahead of print.
INFLUENZA HOUSEHOLD TRANSMISSION AND GENOMIC DIVERSITY IN THE UNITED STATES: A PROSPECTIVE COHORT STUDY, 2022-2024
Sarah N Cox[SUP] 1 [/SUP], Julia C Bennett[SUP] 1 [/SUP], Amanda M Casto[SUP] 2 [/SUP], Katherine L Hoffman[SUP] 3 [/SUP], Collrane Frivold[SUP] 1 [/SUP], Marco Carone[SUP] 3 [/SUP], Zack Acker[SUP] 4 [/SUP], Tara M Babu[SUP] 2 [/SUP], Cassandra L Boisvert[SUP] 5 [/SUP], Brenna Ehmen[SUP] 4 [/SUP], Janet A Englund[SUP] 6 [/SUP], Sally Grindstaff[SUP] 4 [/SUP], Peter Han[SUP] 4 [/SUP], Tara L Hatchie[SUP] 2 [/SUP], Jennifer L Kuntz[SUP] 5 [/SUP], Christina M Lockwood[SUP] 7 [/SUP], Kathryn M McCaffrey[SUP] 4 [/SUP], Richard A Mularski[SUP] 5 [/SUP], Lani Regelbrugge[SUP] 4 [/SUP], Sacha Reich[SUP] 5 [/SUP], Mark A Schmidt[SUP] 5 [/SUP], Ning Smith[SUP] 5 [/SUP], Lea Starita[SUP] 8 [/SUP], Jeremy Stone[SUP] 4 [/SUP], Alexandra Varga[SUP] 5 [/SUP], Ana A Weil[SUP] 9 [/SUP], Allison L Naleway[SUP] 5 [/SUP], Helen Y Chu[SUP] 10 [/SUP]
Affiliations
- PMID: 42019633
- DOI: 10.1016/j.jinf.2026.106748
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.
Keywords: adolescent; adult; community surveillance; epidemiology; genomics; household transmission; influenza; pediatric.