key: cord-0301358-4ejh7oxl
authors: Bruckhaus, A.; Abedi, A.; Salehi, S.; Pickering, T. A.; Zhang, Y.; Martinez, A.; Lai, M.; Garner, R.; Duncan, D.
title: Modeling the COVID-19 Vaccination Dynamics in the United States: An Estimation of Coverage Velocity and Carrying Capacity Based on Socio-demographic Vulnerability Indices in California
date: 2021-07-06
journal: nan
DOI: 10.1101/2021.07.03.21259881
sha: 3f07441b0d233855d1c89dd10f02c585456975f5
doc_id: 301358
cord_uid: 4ejh7oxl

Introduction: Coronavirus disease 2019 (COVID-19) disparities among vulnerable populations are a paramount concern that extends to COVID-19 vaccine administration. We aim to better characterize the scope of vaccine inequity in California by comparing the Social Vulnerability Index (SVI) of California counties and respective vaccination rates, modeling the growth rate and anticipated maximum proportion of individuals vaccinated by SVI group. Methods: Overall SVI, its four themes, and 9228 data points of daily vaccination numbers across all 58 California counties were used to model, overall and by theme, growth velocity of proportion of population vaccinated and the expected maximum proportion of individuals (at least 1 dose of Pfizer-BioNTech, Moderna, or Johnson & Johnson/Janssen) that will be vaccinated for each theme. Results: Overall high vulnerability counties in California have lower vaccine coverage velocity compared to low and moderate vulnerability counties. The largest disparity in coverage velocity between low and highly vulnerable counties was observed in Theme 3 (minority status & language). However, our model showed that highly vulnerable counties based on Theme 3 are expected to eventually achieve a higher proportion of vaccinated individuals compared to low vulnerable counterparts if current trajectories continue. Counties in the overall low vulnerability category are estimated to achieve a higher proportion of vaccinated individuals when compared to high and moderate vulnerable counties, assuming current trajectories. The largest disparity in asymptotic proportion vaccinated between high and low vulnerable counties was observed in Theme 2 (household composition & disability). Conclusion: This study provides insight into the problem of COVID-19 vaccine disparity across California which can be used to help promote equity during the current pandemic as well as guide the allocation of future vaccines such as COVID-19 booster shots.

vaccinated and the expected maximum proportion of individuals (at least 1 dose of Pfizer-BioNTech, Moderna, or Johnson & Johnson/Janssen) that will be vaccinated for each theme.

Results: Overall high vulnerability counties in California have lower vaccine coverage velocity compared to low and moderate vulnerability counties. The largest disparity in coverage velocity between low and highly vulnerable counties was observed in Theme 3 (minority status & language). However, our model showed that highly vulnerable counties based on Theme 3 are expected to eventually achieve a higher proportion of vaccinated individuals compared to low vulnerable counterparts if current trajectories continue. Counties in the overall low vulnerability category are estimated to achieve a higher proportion of vaccinated individuals when compared to high and moderate vulnerable counties, assuming current trajectories. The largest disparity in asymptotic proportion vaccinated between high and low vulnerable counties was observed in (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted July 6, 2021. ; https://doi.org/10.1101/2021.07.03.21259881 doi: medRxiv preprint likely to become hospitalized and Black people are 1.9 times more likely to die from COVID-19 1 . Regarding vaccine administration, White people have received at least one dose of the COVID-19 vaccine at a rate 1.5 times higher than Black people and 1.3 times higher than Hispanic people 2 . California has taken measures to address these inequities, such as dedicating an increased allocation of COVID-19 vaccines for the hardest hit communities while also implementing outreach programs to provide resources and information for these communities. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted July 6, 2021. ; https://doi.org/10.1101/2021.07.03.21259881 doi: medRxiv preprint such as a CDC report published in March 2021 4 . The proportion of vaccinated residents in each county (at least one dose of Pfizer-BioNTech, Moderna, or Johnson & Johnson/Janssen) was used to determine the vaccine coverage across California counties. Together, these two measures were used to model, overall and by theme, the growth velocity of the proportion of population vaccinated, and to estimate the expected maximum proportion of individuals that will be vaccinated. The shape of the longitudinal curves of cumulative vaccination status for each county resembled a logistic growth curve, such as those traditionally used in ecology to describe the growth of a population towards an asymptotic value. Therefore, we used nonlinear ecological growth curves to describe the per capita growth rate ("vaccination velocity", v) and carrying capacity ("asymptotic maximum", K) of populations within each category of the overall and themed SVI.

The nonlinear ecological growth curve approach allowed us to conduct meaningful hypothesis testing of the v and K parameters across counties of differing SVI status. To assess the acceptability of our models, the ecological growth curve models were compared to cubic spline models and the "null" ecological growth models without an effect of SVI status. The R 2 values for the models with the effect of SVI suggested meaningful differences in longitudinal curves among counties of differing SVI status. Overall, high vulnerability counties in California had a lower vaccine coverage velocity compared with low and moderate vulnerability counties. The largest disparity in coverage velocity between low and high vulnerability counties was observed in Theme 3 (minority status & language). However, assuming the continuation of the current trajectory, our model showed that highly vulnerable counties based on Theme 3 are expected to eventually achieve a higher proportion of vaccinated individuals compared with low All rights reserved. No reuse allowed without permission.

(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted July 6, 2021. ; https://doi.org/10.1101/2021.07.03.21259881 doi: medRxiv preprint vulnerability counterparts. Additionally, for the overall SVI category, low vulnerability counties are estimated to achieve a higher proportion of vaccinated individuals when compared with high and moderate vulnerability counties. The largest disparity between the high and low vulnerability counties in the asymptotic proportion of the vaccinated population was observed in Theme 2 (household composition & disability).

Our study suggests that SVI is a useful measure to identify the most vulnerable populations, which can be used as guidance to help mitigate health inequities as recommended by The National Academies of Sciences, Engineering, and Medicine (NASEM) 5 . Furthermore, for the Theme 3 SVI category, although high vulnerability counties yielded the lowest vaccine coverage velocity, this population is expected to ultimately have a higher proportion of vaccinated individuals than low and moderate vulnerability Theme 3 counties. This finding emphasizes the importance of continued intervention by the California government, such as outreach programming and increased allocation of resources to these vulnerable communities. It is also important to recognize that vaccine inequities are rooted in challenges to accessibility and allocation strategies rather than simply a product of vaccine hesitancy. This study provides insight into COVID-19 vaccine disparity across California and can be used to help promote equity during the current pandemic and guide the allocation of future vaccines such as COVID-19 booster shots.

This study was supported by the National Science Foundation (NSF) under Award Number 2027456 (COVID-ARC). This publication was supported by grants UL1TR001855 and UL1TR000130 from the National Center for Advancing Translational Science (NCATS) of the All rights reserved. No reuse allowed without permission.

(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted July 6, 2021. ; https://doi.org/10.1101/2021.07.03.21259881 doi: medRxiv preprint

Risk for COVID-19 Infection, Hospitalization, and Death by Race/Ethnicity. Centers for Disease Control and Prevention (CDC)

Latest Data on COVID-19 Vaccinations by Race/Ethnicity. KFF. Published 2021. Accessed

As California Surpasses 30 Million Vaccines, Governor Newsom Doubles Down on Efforts to Vaccinate Hard-to-Reach Communities. California Governor

County-Level COVID-19 Vaccination Coverage and Social Vulnerability -United States

In: Framework for Equitable Allocation of COVID-19 Vaccine. The National Academies Press

All rights reserved. No reuse allowed without permission.(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint this version posted July 6, 2021. ; https://doi.org/10.1101/2021.07.03.21259881 doi: medRxiv preprint