Tweet
Clin Infect Dis
. 2023 May 29;ciad322.
doi: 10.1093/cid/ciad322. Online ahead of print. High-dose influenza vaccine is associated with reduced mortality among older adults with breakthrough influenza even when there is poor vaccine-strain match
Sandra S Chaves 1 , Sarah Naeger 1 , Kahina Lounaci 2 , Yue Zuo 2 , Matthew M Loiacono 3 , Quentin Pilard 2 , Joshua Nealon 4 , Marie Genin 2 , Cedric Mahe 1
Affiliations
Background: High-dose (HD) influenza vaccine offers improved protection from influenza virus infection among older adults compared with standard-dose (SD) vaccine. Here we explored whether HD vaccine attenuates disease severity among older adults with breakthrough influenza.
Methods: Retrospective cohort study among adults ≥65 years from U.S. claims data, for seasons 2016-17, 2017-18 and 2018-19 defined as October 1st through April 30th. After adjusting the different cohorts for the probability of vaccination conditional on patients' characteristics, we compared 30-day mortality rate post-influenza among older adults experiencing breakthrough infection after receipt of HD or SD influenza vaccines and among those not vaccinated (NV).
Results: We evaluated 44,456 influenza cases: 23,109 (52%) were unvaccinated, 15,037 (33.8%) received HD vaccine and 6,310 (14.2%) received SD vaccine. Significant reductions in mortality rates among breakthrough cases were observed across all three seasons for HD vs NV, ranging from 17-29% reductions. A significant mortality reduction of 25% was associated with SD vaccination vs. NV in the 2016-17 season, when there was a good match between circulating influenza viruses and selected vaccine strains. When comparing HD vs. SD cohorts, mortality reductions were higher among those receiving HD in the last two seasons, when mismatch between vaccine strains and circulating H3N2 viruses were documented, albeit not significant.
Conclusion: HD vaccination was associated with lower post-influenza mortality among older adults with breakthrough influenza, even during seasons where antigenically drifted H3N2 circulated. Improved understanding of the impact of different vaccines on attenuating disease severity is warrant when assessing vaccine policy recommendations.
Keywords: Influenza; breakthrough influenza; disease attenuation; high dose influenza vaccine; severe influenza.
. 2023 May 29;ciad322.
doi: 10.1093/cid/ciad322. Online ahead of print. High-dose influenza vaccine is associated with reduced mortality among older adults with breakthrough influenza even when there is poor vaccine-strain match
Sandra S Chaves 1 , Sarah Naeger 1 , Kahina Lounaci 2 , Yue Zuo 2 , Matthew M Loiacono 3 , Quentin Pilard 2 , Joshua Nealon 4 , Marie Genin 2 , Cedric Mahe 1
Affiliations
- PMID: 37247308
- DOI: 10.1093/cid/ciad322
Background: High-dose (HD) influenza vaccine offers improved protection from influenza virus infection among older adults compared with standard-dose (SD) vaccine. Here we explored whether HD vaccine attenuates disease severity among older adults with breakthrough influenza.
Methods: Retrospective cohort study among adults ≥65 years from U.S. claims data, for seasons 2016-17, 2017-18 and 2018-19 defined as October 1st through April 30th. After adjusting the different cohorts for the probability of vaccination conditional on patients' characteristics, we compared 30-day mortality rate post-influenza among older adults experiencing breakthrough infection after receipt of HD or SD influenza vaccines and among those not vaccinated (NV).
Results: We evaluated 44,456 influenza cases: 23,109 (52%) were unvaccinated, 15,037 (33.8%) received HD vaccine and 6,310 (14.2%) received SD vaccine. Significant reductions in mortality rates among breakthrough cases were observed across all three seasons for HD vs NV, ranging from 17-29% reductions. A significant mortality reduction of 25% was associated with SD vaccination vs. NV in the 2016-17 season, when there was a good match between circulating influenza viruses and selected vaccine strains. When comparing HD vs. SD cohorts, mortality reductions were higher among those receiving HD in the last two seasons, when mismatch between vaccine strains and circulating H3N2 viruses were documented, albeit not significant.
Conclusion: HD vaccination was associated with lower post-influenza mortality among older adults with breakthrough influenza, even during seasons where antigenically drifted H3N2 circulated. Improved understanding of the impact of different vaccines on attenuating disease severity is warrant when assessing vaccine policy recommendations.
Keywords: Influenza; breakthrough influenza; disease attenuation; high dose influenza vaccine; severe influenza.