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J Infect Dis
. 2025 Feb 1:jiaf038.
doi: 10.1093/infdis/jiaf038. Online ahead of print. Influenza vaccine averted illnesses in Chile, Guyana, and Paraguay during 2013-2018: a standardized approach to assess value of vaccination
Jorge H Jara 1 , Sergio Loayza 2 , Francisco Nogareda 1 , Paula Couto 3 , Miguel Angel Descalzo 3 , Anna N Chard 4 , Maria Olivares 5 , Natalia Vergara 5 , Rodrigo Fasce 6 , Martha Von Horoch 7 , Silvia Battaglia 7 , Elena Penayo 7 , Chavely Montserrat Dominguez 7 , Cynthia Vazquez 8 , Rainier Escalada 9 , Janice Woolford 10 , Fabiana Michel 11 , Rafael Chacón 12 , Ashley Fowlkes 4 , Laura Castro 4 , Martha Velandia-Gonzalez 1 , Marc Rondy 3 , Eduardo Azziz-Baumgartner 4 , Stefano Tempia 13 , Daniel Salas 1
Affiliations
Background: To better establish the value of vaccination against influenza viruses, we estimated vaccine-averted influenza illnesses among young children and older adults in Chile, Guyana, and Paraguay.
Methods: We gathered country- and target population-specific data on monthly influenza hospitalizations, vaccine coverage, and vaccine effectiveness from surveillance records and immunization registries during 2013-2018. We applied a static compartmental model to estimate differences in the number influenza-associated respiratory disease events (symptomatic non-hospitalized illnesses, medically attended illnesses, hospitalizations) in the presence and absence of influenza vaccination programs.
Results: Between 2013 and 2018, vaccinating 68% of children aged 6-23 months in Chile averted an annual mean of 14,617 non-hospitalized, 9,426 medically attended, and 328 hospitalized influenza illnesses; vaccinating 28% of children aged 6-23 months in Paraguay averted 1,115 non-hospitalized, 719 medically attended, and 25 hospitalized influenza illnesses. Vaccinating 59% of older adults in Chile averted an annual mean of 83,429 non-hospitalized, 37,079 medically attended, and 1,390 hospitalized influenza illnesses; vaccinating 36% of older adults in Paraguay averted an annual mean of 3,932 non-hospitalized, 1,748 medically attended, and 66 hospitalized influenza illnesses. In Guyana, a hypothetical campaign vaccinating 30% of children <5 years could have prevented an annual 1,496 non-hospitalized, 971 medically attended, and 10 hospitalized influenza illnesses. Vaccinating 30% of adults ≥65 years could have prevented 568 non-hospitalized, 257 medically attended, and 10 hospitalized influenza illnesses.
Conclusions: Influenza vaccination averted tens of thousands of illnesses and thousands of hospitalizations in Chile and Paraguay; influenza vaccination could have had a proportional benefit in Guyana.
Keywords: Averted illness; Influenza burden; Influenza vaccine; Vaccine effectiveness.
. 2025 Feb 1:jiaf038.
doi: 10.1093/infdis/jiaf038. Online ahead of print. Influenza vaccine averted illnesses in Chile, Guyana, and Paraguay during 2013-2018: a standardized approach to assess value of vaccination
Jorge H Jara 1 , Sergio Loayza 2 , Francisco Nogareda 1 , Paula Couto 3 , Miguel Angel Descalzo 3 , Anna N Chard 4 , Maria Olivares 5 , Natalia Vergara 5 , Rodrigo Fasce 6 , Martha Von Horoch 7 , Silvia Battaglia 7 , Elena Penayo 7 , Chavely Montserrat Dominguez 7 , Cynthia Vazquez 8 , Rainier Escalada 9 , Janice Woolford 10 , Fabiana Michel 11 , Rafael Chacón 12 , Ashley Fowlkes 4 , Laura Castro 4 , Martha Velandia-Gonzalez 1 , Marc Rondy 3 , Eduardo Azziz-Baumgartner 4 , Stefano Tempia 13 , Daniel Salas 1
Affiliations
- PMID: 39891541
- DOI: 10.1093/infdis/jiaf038
Background: To better establish the value of vaccination against influenza viruses, we estimated vaccine-averted influenza illnesses among young children and older adults in Chile, Guyana, and Paraguay.
Methods: We gathered country- and target population-specific data on monthly influenza hospitalizations, vaccine coverage, and vaccine effectiveness from surveillance records and immunization registries during 2013-2018. We applied a static compartmental model to estimate differences in the number influenza-associated respiratory disease events (symptomatic non-hospitalized illnesses, medically attended illnesses, hospitalizations) in the presence and absence of influenza vaccination programs.
Results: Between 2013 and 2018, vaccinating 68% of children aged 6-23 months in Chile averted an annual mean of 14,617 non-hospitalized, 9,426 medically attended, and 328 hospitalized influenza illnesses; vaccinating 28% of children aged 6-23 months in Paraguay averted 1,115 non-hospitalized, 719 medically attended, and 25 hospitalized influenza illnesses. Vaccinating 59% of older adults in Chile averted an annual mean of 83,429 non-hospitalized, 37,079 medically attended, and 1,390 hospitalized influenza illnesses; vaccinating 36% of older adults in Paraguay averted an annual mean of 3,932 non-hospitalized, 1,748 medically attended, and 66 hospitalized influenza illnesses. In Guyana, a hypothetical campaign vaccinating 30% of children <5 years could have prevented an annual 1,496 non-hospitalized, 971 medically attended, and 10 hospitalized influenza illnesses. Vaccinating 30% of adults ≥65 years could have prevented 568 non-hospitalized, 257 medically attended, and 10 hospitalized influenza illnesses.
Conclusions: Influenza vaccination averted tens of thousands of illnesses and thousands of hospitalizations in Chile and Paraguay; influenza vaccination could have had a proportional benefit in Guyana.
Keywords: Averted illness; Influenza burden; Influenza vaccine; Vaccine effectiveness.