tetano
Editor, Senior Moderator
Lancet Glob Health
. 2025 Feb;13(2):e203-e211.
doi: 10.1016/S2214-109X(24)00473-X. Effectiveness of 2023 southern hemisphere influenza vaccines against severe influenza-associated illness: pooled estimates from eight countries using the test-negative design
Radhika Gharpure[SUP] 1 [/SUP], Annette K Regan[SUP] 2 [/SUP], Francisco Nogareda[SUP] 3 [/SUP], Allen C Cheng[SUP] 4 [/SUP], Christopher C Blyth[SUP] 5 [/SUP], Siobhan St George[SUP] 6 [/SUP], Q Sue Huang[SUP] 7 [/SUP], Tim Wood[SUP] 7 [/SUP], Andrew Anglemyer[SUP] 7 [/SUP], Kriengkrai Prasert[SUP] 8 [/SUP], Prabda Praphasiri[SUP] 9 [/SUP], William W Davis[SUP] 10 [/SUP], Chakrarat Pittayawonganon[SUP] 11 [/SUP], Regina Ercole[SUP] 12 [/SUP], Analia Iturra[SUP] 13 [/SUP], Walquiria Aparecida Ferreira de Almeida[SUP] 14 [/SUP], Francisco José de Paula Júnior[SUP] 14 [/SUP], Marcela Avendaño Vigueras[SUP] 15 [/SUP], Maria Fernanda Olivares Barraza[SUP] 16 [/SUP], Chavely Domínguez[SUP] 17 [/SUP], Elena Penayo[SUP] 17 [/SUP], Natalia Goñi[SUP] 18 [/SUP], Daiana Tritten[SUP] 19 [/SUP], Paula Couto[SUP] 3 [/SUP], Daniel Salas[SUP] 3 [/SUP], Ashley L Fowlkes[SUP] 1 [/SUP], Lindsey M Duca[SUP] 1 [/SUP], Eduardo Azziz-Baumgartner[SUP] 1 [/SUP], Sheena G Sullivan[SUP] 20 [/SUP]
Affiliations
Background: Annual estimates of seasonal influenza vaccine effectiveness can guide global risk communication and vaccination strategies to mitigate influenza-associated illness. We aimed to evaluate vaccine effectiveness in countries using the 2023 southern hemisphere influenza vaccine formulation.
Methods: We evaluated end-of-season influenza vaccine effectiveness across eight countries (Argentina, Australia, Brazil, Chile, New Zealand, Paraguay, Thailand, and Uruguay) that used the 2023 southern hemisphere vaccine formulation, with use of a test-negative design. All patients who attended participating hospitals with severe acute respiratory illness were tested by RT-PCR for influenza. We calculated country-specific, network-specific, and pooled vaccine effectiveness against hospitalisation. For countries with sufficient data, we also calculated vaccine effectiveness against intensive care unit (ICU) admission by comparing the odds of vaccination among test-positive cases to that among test-negative controls. We evaluated vaccine effectiveness for groups prioritised for vaccination (young children aged 1-4 years, people aged 5-64 years with underlying health conditions, and older adults aged ≥65 years).
Findings: From March 5 to Nov 27, 2023, 31 368 individuals were admitted to hospital with severe acute respiratory infection in the eight included countries. Of these, 12 609 individuals admitted to hospital (6452 [51·2%] female and 6157 [48·8%] male) who met inclusion criteria and had complete data were included in the analysis, including 4388 test-positive cases and 8221 test-negative controls. Pooled vaccine effectiveness against hospitalisation with any influenza virus was 51·9% (95% CI 37·2-66·7), with substantial heterogeneity across countries (I[SUP]2[/SUP] 74%). Vaccine effectiveness against ICU admission from any influenza virus was 67·7% (44·5-81·2) in Chile and 69·7% (45·3-83·3) in Australia. Vaccine effectiveness estimates against hospitalisation were highest for young children (70·9% [47·5-94·4]) and lowest for older adults (47·7% [24·9-70·5]).
Interpretation: Across eight countries, 2023 southern hemisphere vaccines were effective in reducing hospitalisations from influenza illness. Use of common protocols can facilitate data pooling to provide a comprehensive evaluation of vaccine effectiveness across settings.
Funding: US Centers for Disease Control and Prevention cooperative agreements to the Pan American Health Organization and the Thailand Ministry of Public Health; the Australian Government Department of Health and Aged Care; and the New Zealand Ministry of Health.
. 2025 Feb;13(2):e203-e211.
doi: 10.1016/S2214-109X(24)00473-X. Effectiveness of 2023 southern hemisphere influenza vaccines against severe influenza-associated illness: pooled estimates from eight countries using the test-negative design
Radhika Gharpure[SUP] 1 [/SUP], Annette K Regan[SUP] 2 [/SUP], Francisco Nogareda[SUP] 3 [/SUP], Allen C Cheng[SUP] 4 [/SUP], Christopher C Blyth[SUP] 5 [/SUP], Siobhan St George[SUP] 6 [/SUP], Q Sue Huang[SUP] 7 [/SUP], Tim Wood[SUP] 7 [/SUP], Andrew Anglemyer[SUP] 7 [/SUP], Kriengkrai Prasert[SUP] 8 [/SUP], Prabda Praphasiri[SUP] 9 [/SUP], William W Davis[SUP] 10 [/SUP], Chakrarat Pittayawonganon[SUP] 11 [/SUP], Regina Ercole[SUP] 12 [/SUP], Analia Iturra[SUP] 13 [/SUP], Walquiria Aparecida Ferreira de Almeida[SUP] 14 [/SUP], Francisco José de Paula Júnior[SUP] 14 [/SUP], Marcela Avendaño Vigueras[SUP] 15 [/SUP], Maria Fernanda Olivares Barraza[SUP] 16 [/SUP], Chavely Domínguez[SUP] 17 [/SUP], Elena Penayo[SUP] 17 [/SUP], Natalia Goñi[SUP] 18 [/SUP], Daiana Tritten[SUP] 19 [/SUP], Paula Couto[SUP] 3 [/SUP], Daniel Salas[SUP] 3 [/SUP], Ashley L Fowlkes[SUP] 1 [/SUP], Lindsey M Duca[SUP] 1 [/SUP], Eduardo Azziz-Baumgartner[SUP] 1 [/SUP], Sheena G Sullivan[SUP] 20 [/SUP]
Affiliations
- PMID: 39890222
- PMCID: PMC11783037
- DOI: 10.1016/S2214-109X(24)00473-X
Background: Annual estimates of seasonal influenza vaccine effectiveness can guide global risk communication and vaccination strategies to mitigate influenza-associated illness. We aimed to evaluate vaccine effectiveness in countries using the 2023 southern hemisphere influenza vaccine formulation.
Methods: We evaluated end-of-season influenza vaccine effectiveness across eight countries (Argentina, Australia, Brazil, Chile, New Zealand, Paraguay, Thailand, and Uruguay) that used the 2023 southern hemisphere vaccine formulation, with use of a test-negative design. All patients who attended participating hospitals with severe acute respiratory illness were tested by RT-PCR for influenza. We calculated country-specific, network-specific, and pooled vaccine effectiveness against hospitalisation. For countries with sufficient data, we also calculated vaccine effectiveness against intensive care unit (ICU) admission by comparing the odds of vaccination among test-positive cases to that among test-negative controls. We evaluated vaccine effectiveness for groups prioritised for vaccination (young children aged 1-4 years, people aged 5-64 years with underlying health conditions, and older adults aged ≥65 years).
Findings: From March 5 to Nov 27, 2023, 31 368 individuals were admitted to hospital with severe acute respiratory infection in the eight included countries. Of these, 12 609 individuals admitted to hospital (6452 [51·2%] female and 6157 [48·8%] male) who met inclusion criteria and had complete data were included in the analysis, including 4388 test-positive cases and 8221 test-negative controls. Pooled vaccine effectiveness against hospitalisation with any influenza virus was 51·9% (95% CI 37·2-66·7), with substantial heterogeneity across countries (I[SUP]2[/SUP] 74%). Vaccine effectiveness against ICU admission from any influenza virus was 67·7% (44·5-81·2) in Chile and 69·7% (45·3-83·3) in Australia. Vaccine effectiveness estimates against hospitalisation were highest for young children (70·9% [47·5-94·4]) and lowest for older adults (47·7% [24·9-70·5]).
Interpretation: Across eight countries, 2023 southern hemisphere vaccines were effective in reducing hospitalisations from influenza illness. Use of common protocols can facilitate data pooling to provide a comprehensive evaluation of vaccine effectiveness across settings.
Funding: US Centers for Disease Control and Prevention cooperative agreements to the Pan American Health Organization and the Thailand Ministry of Public Health; the Australian Government Department of Health and Aged Care; and the New Zealand Ministry of Health.