PURPOSE: The U.S. Virgin Islands (USVI) receives an updated population count once every 10 years and used 2010 decennial census population counts to estimate COVID-19 vaccination coverage during the COVID-19 emergency response. We investigated whether using outdated (2010) or modeled (2020 international database [IDB]) population counts biased vaccination coverage estimates used to inform public health priorities during the 2020-2022 COVID-19 response. METHODS: We estimated percentage of USVI residents with a completed primary COVID-19 vaccination series during December 16, 2020-September 20, 2022. Vaccination coverage was calculated as number of persons who completed the vaccination series divided by 2010 and 2020 decennial census population counts and 2020 IDB intercensal estimate. RESULTS: COVID-19 vaccination coverage using the 2020 population count was 12 percentage points higher than coverage using 2010 denominator (2010 denominator: 51%; 2020 denominator: 63%). Vaccination coverage estimated using 2020 IDB was approximately equal with the 2010 decennial census estimate (52%). CONCLUSIONS: Using 2010 and modeled population counts underestimated 2020 USVI COVID-19 vaccination coverage given the 18% population decline during 2010-2020, potentially limiting USVI's ability to assess vaccination progress. Identifying mechanisms for more reliable population enumeration or improved estimate modeling are essential for accurately guiding USVI public health decision-making.

On February 1, 2022, the U.S. Virgin Islands (USVI) Department of Health (VIDOH) was notified of a confirmed case of Legionnaires disease in an adult U.S. resident (Figure). The patient, a man aged 55 years, returned to his U.S. state of residence from leisure travel in USVI on January 22 and developed a cough, shortness of breath, and fatigue on January 23. On January 29, he was hospitalized for shortness of breath and received a positive SARS-CoV-2 test result at admission. The combination of the patient’s symptoms and recent travel history prompted administration of a urinary antigen test (UAT) for Legionnaires disease specific to Legionella pneumophila serogroup 1 (Lp1); a positive result was returned on January 31. Inpatient treatment administered for COVID-19 pneumonia and Legionnaires disease included remdesivir, oral levofloxacin, oral and intravenous steroid therapy, and as-needed use of a bronchodilator inhaler and an expectorant. Remdesivir was discontinued during inpatient treatment because of elevated liver enzymes. The patient recovered and was discharged on February 2.

In May 2019, the Food and Drug Administration issued approval for Dengvaxia (Sanofi Pasteur), a live-attenuated, chimeric tetravalent dengue vaccine (1). In June 2021, the Advisory Committee on Immunization Practices (ACIP) recommended vaccination with Dengvaxia for children and adolescents aged 9–16 years with laboratory confirmation of previous dengue virus infection and who live in areas with endemic dengue transmission, such as the U.S. Virgin Islands (USVI)† (2). Confirming previous dengue virus infection before vaccine administration (prevaccination screening) is important because 1) although Dengvaxia decreases hospitalization and severe disease from dengue among persons with a previous infection, it increases the risk for these outcomes among persons without a previous infection; 2) many dengue virus infections are asymptomatic; and 3) many patients with symptomatic infections do not seek medical attention or receive appropriate testing (3). Sufficient laboratory evidence of previous dengue virus infection includes a history of laboratory-confirmed dengue§ or a positive serologic test result that meets ACIP-recommended performance standards for prevaccination screening, defined as high specificity (≥98%) and sensitivity (≥75%). A seroprevalence of 20% in the vaccine-eligible population (corresponding to a positive predictive value of ≥90% for a test with minimum sensitivity of 75% and minimum specificity of 98%) is recommended to maximize vaccine safety and minimize the risk for vaccinating persons without a previous dengue virus infection (2).