Introduction: Operational units routinely screen personnel prior to deployment and redeployment with written questionnaires and coronavirus disease 2019 (COVID-19) testing. However, active-duty compliance with the optional COVID-19 booster vaccination remains incomplete, with yet unknown implications for force readiness. In this study, we examine the relationship between the COVID-19 vaccine booster and up-to-date immunization on the incidence of positive COVID-19 cases in an active-duty unit undergoing routine travel screening. Materials and Methods: After IRB approval, a retrospective chart review was conducted of 800 fully vaccinated active-duty service members (ADSMs) undergoing travel restriction of movement exit testing (TRET) over one week from 17 February 2022 to 23 February 2022. Service members were defined as fully vaccinated per Centers for Disease Control and Prevention (CDC) guidelines at the time of this study: at least 2 weeks status post the BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) COVID-19 two dose vaccine primary series or Ad26.COV2.S (Janssen/Johnson and Johnson) one dose COVID-19 primary vaccine series. Service members were considered up-to-date (UTD) if within 5 months of receiving the BNT162b2 or mRNA-1273 two dose vaccine primary series or within 2 months of receiving the Ad26.COV2.S one dose primary vaccine series, or within any time after receiving an eligible COVID-19 booster dose. Fully vaccinated ADSMs that did not meet the criteria for UTD were considered not up-to-date (not-UTD). Those that received an eligible booster dose at any time were considered ‘boosted’ and all others ‘not boosted.’ Patient age, branch, sex, and vaccination status were compiled electronically. Results: Of 800 fully vaccinated ADSMs, 674 met inclusion criteria. ADSMs were evenly split between those who were UTD (n=337, 50%) and not-UTD (n=337, 50%). Those who were up-to-date on their COVID-19 vaccinations were slightly older (23.7 years vs. 23.0 years, p=.011) and more likely to be employed by the US Navy (10.1% vs. 3.6%, p<.001). Of 4 ADSMs that tested positive during TRET, there was not a significant difference in the number of positive tests between ADSMs who were or were not up-to-date on their vaccinations (0.6% vs. 0.6%, p=1.00), and all were asymptomatic when screened. There was likewise no significant difference in the number of positive tests between asymptomatic ADSMs who did or did not receive a booster (0.4% vs. 0.7%, p=1.00). Conclusions: Our results suggest that among fully vaccinated active-duty service members, the COVID-19 booster and up-to-date immunization status may not impact routine travel screening results.