tetano
Editor, Senior Moderator
Clin Infect Dis
. 2025 Jan 6:ciae658.
doi: 10.1093/cid/ciae658. Online ahead of print. Influenza vaccine effectiveness against medically attended outpatient illness, United States, 2023-24 season
Jessie R Chung[SUP] 1 [/SUP], Ashley M Price[SUP] 1 [/SUP], Richard K Zimmerman[SUP] 2 [/SUP], Krissy Moehling Geffel[SUP] 2 [/SUP], Stacey L House[SUP] 3 [/SUP], Tara Curley[SUP] 3 [/SUP], Karen J Wernli[SUP] 4 5 [/SUP], C Hallie Phillips[SUP] 4 [/SUP], Emily T Martin[SUP] 6 [/SUP], Ivana A Vaughn[SUP] 7 [/SUP], Vel Murugan[SUP] 8 [/SUP], Matthew Scotch[SUP] 8 [/SUP], Elie A Saade[SUP] 9 [/SUP], Kiran A Faryar[SUP] 9 [/SUP], Manjusha Gaglani[SUP] 10 11 [/SUP], Jason D Ramm[SUP] 10 11 [/SUP], Olivia L Williams[SUP] 12 [/SUP], Emmanuel B Walter[SUP] 12 [/SUP], Marie Kirby[SUP] 1 [/SUP], Lisa M Keong[SUP] 1 [/SUP], Rebecca Kondor[SUP] 1 [/SUP], Sascha R Ellington[SUP] 1 [/SUP], Brendan Flannery[SUP] 1 [/SUP]; US Flu VE Network Investigators
Collaborators, Affiliations
Background: The 2023-24 U.S. influenza season was characterized by a predominance of A(H1N1)pdm09 virus circulation with co-circulation of A(H3N2) and B/Victoria viruses. We estimated vaccine effectiveness (VE) in the United States against mild-to-moderate medically attended influenza illness in the 2023-24 season.
Methods: We enrolled outpatients aged ≥8 months with acute respiratory illness in 7 states. Respiratory specimens were tested for influenza type/subtype by reverse-transcriptase polymerase chain reaction (RT-PCR). Influenza VE was estimated with a test-negative design comparing odds of testing positive for influenza among vaccinated versus unvaccinated participants. We estimated VE by virus sub-type/lineage and A(H1N1)pdm09 genetic subclades.
Results: Among 6,589 enrolled patients, 1,770 (27%) tested positive for influenza including 796 A(H1N1)pdm09, 563 B/Victoria, and 323 A(H3N2). Vaccine effectiveness against any influenza illness was 41% (95% Confidence Interval [CI]: 32 to 49): 28% (95% CI: 13 to 40) against influenza A(H1N1)pdm09, 68% (95% CI: 59 to 76) against B/Victoria, and 30% (95% CI: 9 to 47) against A(H3N2). Statistically significant protection against any influenza was found for all age groups except adults aged 50-64 years. Lack of protection in this age group was specific to influenza A-associated illness. We observed differences in VE by birth cohort and A(H1N1)pdm09 virus genetic subclade.
Conclusions: Vaccination reduced outpatient medically attended influenza overall by 41% and provided protection overall against circulating influenza A and B viruses. Serologic studies would help inform differences observed by age groups.
Keywords: Influenza; vaccination; vaccine effectiveness.
. 2025 Jan 6:ciae658.
doi: 10.1093/cid/ciae658. Online ahead of print. Influenza vaccine effectiveness against medically attended outpatient illness, United States, 2023-24 season
Jessie R Chung[SUP] 1 [/SUP], Ashley M Price[SUP] 1 [/SUP], Richard K Zimmerman[SUP] 2 [/SUP], Krissy Moehling Geffel[SUP] 2 [/SUP], Stacey L House[SUP] 3 [/SUP], Tara Curley[SUP] 3 [/SUP], Karen J Wernli[SUP] 4 5 [/SUP], C Hallie Phillips[SUP] 4 [/SUP], Emily T Martin[SUP] 6 [/SUP], Ivana A Vaughn[SUP] 7 [/SUP], Vel Murugan[SUP] 8 [/SUP], Matthew Scotch[SUP] 8 [/SUP], Elie A Saade[SUP] 9 [/SUP], Kiran A Faryar[SUP] 9 [/SUP], Manjusha Gaglani[SUP] 10 11 [/SUP], Jason D Ramm[SUP] 10 11 [/SUP], Olivia L Williams[SUP] 12 [/SUP], Emmanuel B Walter[SUP] 12 [/SUP], Marie Kirby[SUP] 1 [/SUP], Lisa M Keong[SUP] 1 [/SUP], Rebecca Kondor[SUP] 1 [/SUP], Sascha R Ellington[SUP] 1 [/SUP], Brendan Flannery[SUP] 1 [/SUP]; US Flu VE Network Investigators
Collaborators, Affiliations
- PMID: 39761230
- DOI: 10.1093/cid/ciae658
Background: The 2023-24 U.S. influenza season was characterized by a predominance of A(H1N1)pdm09 virus circulation with co-circulation of A(H3N2) and B/Victoria viruses. We estimated vaccine effectiveness (VE) in the United States against mild-to-moderate medically attended influenza illness in the 2023-24 season.
Methods: We enrolled outpatients aged ≥8 months with acute respiratory illness in 7 states. Respiratory specimens were tested for influenza type/subtype by reverse-transcriptase polymerase chain reaction (RT-PCR). Influenza VE was estimated with a test-negative design comparing odds of testing positive for influenza among vaccinated versus unvaccinated participants. We estimated VE by virus sub-type/lineage and A(H1N1)pdm09 genetic subclades.
Results: Among 6,589 enrolled patients, 1,770 (27%) tested positive for influenza including 796 A(H1N1)pdm09, 563 B/Victoria, and 323 A(H3N2). Vaccine effectiveness against any influenza illness was 41% (95% Confidence Interval [CI]: 32 to 49): 28% (95% CI: 13 to 40) against influenza A(H1N1)pdm09, 68% (95% CI: 59 to 76) against B/Victoria, and 30% (95% CI: 9 to 47) against A(H3N2). Statistically significant protection against any influenza was found for all age groups except adults aged 50-64 years. Lack of protection in this age group was specific to influenza A-associated illness. We observed differences in VE by birth cohort and A(H1N1)pdm09 virus genetic subclade.
Conclusions: Vaccination reduced outpatient medically attended influenza overall by 41% and provided protection overall against circulating influenza A and B viruses. Serologic studies would help inform differences observed by age groups.
Keywords: Influenza; vaccination; vaccine effectiveness.