Changing COVID-19 vaccine eligibility could reshape disease burden for all
Abstract
COVID-19 vaccine recommendations have changed in the United States over the past year, raising questions about the likely impact on disease dynamics. While older adults are most at risk of severe COVID-19 outcomes and therefore experience the greatest direct benefits of vaccination, limiting vaccination to only this age group could worsen outcomes in this higher-risk population through indirect effects. Here, we leveraged survey data on age-specific vaccine uptake, and surveillance data from Illinois to calibrate a transmission model accounting for contact and vaccination rates across age. We simulated four years of COVID-19 transmission under three scenarios: vaccination uptake across all ages, vaccination of only those aged 5+, and vaccination of only those aged 65+. Our model suggests that removing those under 65+ from eligibility could increase hospitalizations by 23-27% across age groups, signaling that vaccination coverage among younger adults and children substantially mitigates COVID-19 hospitalization burden for older populations. Moreover, while children would experience the greatest per capita increase in infections, older adults would experience the greatest per capita increase in hospitalizations. The full scope of consequences for disease burden may not be observed until after the first year of the policy change. These findings highlight the long-term consequences of deprioritizing young adults and children from vaccination campaigns, and show that gaps in vaccine-induced immunity can shape outcomes in other age groups. This underscores the importance of considering indirect vaccine impacts when developing policy.
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BibTeX
@misc{larsen2026changing,
title = {{Changing COVID-19 vaccine eligibility could reshape disease burden for all}},
author = {Soren L. Larsen and Pamela P. Martinez and Ayesha S. Mahmud},
howpublished = {medRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.04.27.26351870},
url = {https://doi.org/10.64898/2026.04.27.26351870},
note = {CC BY-NC 4.0},
}
RIS
TY - UNPB
TI - Changing COVID-19 vaccine eligibility could reshape disease burden for all
AU - Soren L. Larsen
AU - Pamela P. Martinez
AU - Ayesha S. Mahmud
PY - 2026
DA - 2026/10/21
PB - medRxiv
DO - 10.64898/2026.04.27.26351870
UR - https://doi.org/10.64898/2026.04.27.26351870
AB - COVID-19 vaccine recommendations have changed in the United States over the past year, raising questions about the likely impact on disease dynamics. While older adults are most at risk of severe COVID-19 outcomes and therefore experience the greatest direct benefits of vaccination, limiting vaccination to only this age group could worsen outcomes in this higher-risk population through indirect effects. Here, we leveraged survey data on age-specific vaccine uptake, and surveillance data from Illinois to calibrate a transmission model accounting for contact and vaccination rates across age. We simulated four years of COVID-19 transmission under three scenarios: vaccination uptake across all ages, vaccination of only those aged 5+, and vaccination of only those aged 65+. Our model suggests that removing those under 65+ from eligibility could increase hospitalizations by 23-27% across age groups, signaling that vaccination coverage among younger adults and children substantially mitigates COVID-19 hospitalization burden for older populations. Moreover, while children would experience the greatest per capita increase in infections, older adults would experience the greatest per capita increase in hospitalizations. The full scope of consequences for disease burden may not be observed until after the first year of the policy change. These findings highlight the long-term consequences of deprioritizing young adults and children from vaccination campaigns, and show that gaps in vaccine-induced immunity can shape outcomes in other age groups. This underscores the importance of considering indirect vaccine impacts when developing policy.
ER -