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. 2025 Apr 14:30:101804.
doi: 10.1016/j.ssmph.2025.101804. eCollection 2025 Jun.

Disparity between expected spatial accessibility and actual travel time to vaccination sites: Implications for COVID-19 immunization delays

Hossein Naderi  1 , Ziba Abbasian  2 , Yuxia Huang  1
Affiliations

Disparity between expected spatial accessibility and actual travel time to vaccination sites: Implications for COVID-19 immunization delays

Hossein Naderi et al. SSM Popul Health. .

Abstract

The COVID-19 pandemic underscored the importance of equitable and timely vaccination access. This study examined the impact of discrepancies between actual and expected travel times to vaccination centers on the timeliness of full and booster COVID-19 vaccinations in Nueces County, Texas. Drawing on vaccination data from over 171,000 individuals aged 18 and older, we employed Cox proportional hazards models and survival analysis to explore how demographic characteristics, the Social Vulnerability Index (SVI), and geographic disparities influenced vaccination delays. Results revealed that longer-than-expected travel times significantly reduced the likelihood of timely vaccination (HR = 0.95 for full vaccination, HR = 0.89 for booster doses). Seniors demonstrated higher vaccination timeliness rates, but gaps persisted across gender, ethnicity, and race, with males and Hispanics experiencing greater delays. Interaction analysis highlighted compounded challenges for seniors and vulnerable populations when travel time discrepancies were larger. These findings emphasize the critical need for geographically targeted public health interventions to address socio-economic disparities and improve vaccine accessibility during health crises.

Keywords: COVID-19 vaccine; Health Service Geographic Accessibility; Public health; Survival analysis; Vaccination hesitancy.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Distribution of COVID-19 vaccination sites in Nueces County, Texas.
Fig. 2
Fig. 2
Flowchart of sample selection for the fully vaccinated and booster vaccine analysis.
Fig. 3
Fig. 3
Average travel time discrepancies in the block group level for booster vaccination in Nueces County.
Fig. 4
Fig. 4
Cumulative survival curves for the event (receiving the booster COVID-19 vaccine dose.
See this image and copyright information in PMC

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