Colorado introduces age-adjusted vaccine breakthrough tracking tool

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STATEWIDE (Nov. 10, 2021) — CDPHE will introduce age adjustment to the Vaccine Breakthrough dashboard as part of today’s regular 4 p.m. data update. This update will allow the state to more accurately compare rates between vaccinated and unvaccinated Coloradans, and to bring Colorado’s methods more in line with Centers for Disease Control and Prevention. Age adjustment allows for a more accurate comparison of disease risk between groups with different age distributions. This is important when evaluating vaccine breakthrough data because the age distribution of the vaccinated population is different from the age distribution of the unvaccinated population. The age-adjusted data is based on 10-year age breakouts sourced from 2020 population estimates from the State Demography Office in the Department of Local Affairs (DOLA).

The age distribution among vaccinated and unvaccinated Coloradans varies, in part due to differences in age group eligibility throughout the phased COVID-19 vaccine rollout. Data shows age is an important factor in determining who becomes ill, who is hospitalized, and who dies from COVID-19. Age adjustment allows CDPHE to see what the rates of cases, hospitalizations, and deaths among vaccinated and unvaccinated Coloradans would be if each group had exactly the same age structure. For example, since a vaccinated population likely has a higher percentage of elderly people, that population may have a higher rate of death or hospitalization than an unvaccinated population merely because the elderly are more likely to die or be hospitalized from COVID-19.

This methodology evens out the differences in age distribution to make two populations more comparable, but the rates generated for these comparisons cannot be used to calculate counts of cases, hospitalizations, or deaths. Crude (unadjusted) counts and rates of vaccinated and unvaccinated COVID-19 cases, hospitalizations, and deaths will continue to be published in the Vaccine Breakthrough Data summary file and the CDPHE Vaccine Breakthrough metrics Open Data Portal file

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