Date of Award

January 2025

Document Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

School of Public Health

First Advisor

Albert Ko

Second Advisor

Margaret Lind

Abstract

Importance: Booster doses of the COVID-19 vaccine are critical for maintaining protection against SARS-CoV-2, especially in high-risk settings such as correctional facilities. Understanding how initial vaccine type influences booster uptake can inform vaccination strategies in these and other underserved populations.Objective: To assess whether the type of COVID-19 vaccine received for the primary series—either viral vector (Janssen/Jcovden) or mRNA (Moderna/Spikevax or Pfizer-BioNTech/Comirnaty)—was associated with timing or likelihood of booster completion among incarcerated individuals. Design: Retrospective cohort study using survival analysis methods. The study period spanned from February 2, 2021, to May 31, 2023. Setting: Connecticut Department of Correction (DOC) facilities, including both jails and prisons. Participants: The study included 6,404 individuals who were incarcerated during the study period, completed a primary COVID-19 vaccine series (one dose of Janssen or two doses of Moderna or Pfizer-BioNTech), and became booster eligible while incarcerated. Individuals were excluded if vaccine manufacturer data were missing, if they received a booster before eligibility, or if they left DOC custody before becoming eligible or contributing follow-up time. Exposures: Primary COVID-19 vaccine type: Viral vector (Janssen/Jcovden) or mRNA (Moderna/Spikevax or Pfizer-BioNTech/Comirnaty) Main Outcomes and Measures: Time from booster eligibility to booster receipt. Cox proportional hazards models estimated the association between vaccine type and booster uptake, adjusted for age, gender, and race, and stratified by facility type and calendar month of booster eligibility. Results: Among the 6,404 included individuals, (median age at eligibility: 39 years), 891 received Janssen for their primary series, 4,997 received Moderna, and 516 received Pfizer. Overall, 3,538 individuals (55.2%) received a booster. Median time from primary vaccination completion to booster receipt was 113 days for Janssen recipients, 67 days for Pfizer recipients, and 63 days for Moderna recipients. Compared to Janssen recipients, the adjusted hazard of booster receipt was higher among mRNA (combined) recipients (aHR: 2.02; 95% CI: 1.63–2.50), as well as for Moderna recipients (aHR: 2.14; 95% CI: 1.72–2.66) and Pfizer recipients (aHR: 1.34; 95% CI: 1.03–1.75). Conclusions and Relevance: Primary vaccine type was strongly associated with the timing and likelihood of booster uptake in this incarcerated population. Perceptions shaped by early public health messaging—including concerns around safety and efficacy and the framing of Janssen as a single-dose vaccine—may have influenced future vaccination behavior. Public health campaigns should address concerns raised as new information on vaccine efficacy and safety emerges, which in turn may impact uptake of booster vaccination.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 06/16/2026

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