Characterizing SARS-CoV-2 infection burden and COVID-19 vaccination intent and uptake in congregate shelters in Seattle, WA

Community-based surveillance studies can be appropriately leveraged to characterize the burden of emerging pathogens, especially in hard-to-reach populations such as people experiencing homelessness (PEH). Prior respiratory viral studies among PEH populations have shown evidence of increased morbidity and mortality compared to the general population, likely associated with a high prevalence of co-occurring health conditions, though they are scant and limited to single time-point cross-sectional sampling with small sample sizes. Both homeless shelter residents and staff are at higher risk of SARS-CoV-2 infection because of residing or working in congregate settings. However, reported SARS-CoV-2 infection burden in this population has been variable and reliant on cross-sectional or outbreak investigation data without sufficiently accounting for sociodemographic characteristics and temporal trends. Challenges to reduce severe outcomes related to COVID-19 among PEH include access to COVID-19 vaccination and a history of disproportionately low vaccine intent. Further, understanding the continuum of vaccine intent and how it is unique within shelter populations has not been well elucidated, despite being necessary for successfully tailored COVID-19 vaccination campaigns. In the following dissertation aims, we address these gaps. In Chapter 2 we calculated the incidence of laboratory-confirmed SARS-CoV-2 infection among shelter residents and staff over the study period. We also identified individual-level risk factors associated with SARS-CoV-2 infection among shelter staff vs. shelter residents. Additionally, we identified individual-level risk factors associated with symptomatic COVID-19 compared to asymptomatic infection among all SARS-CoV-2 positive participants. In Chapter 3 we described and assessed the individual-level sociodemographic and health characteristics associated with COVID-19 vaccination intent and uptake among shelter residents and staff. Additionally, we evaluated population-level and within-person changes in vaccination intent and uptake using repeated measures over the study period. To accomplish these aims, we leveraged data from an active surveillance study of acute respiratory illness (ARI) and asymptomatic viral infection in congregate shelters in the Seattle-King County area, conducted from 1 October 2019 through 31 May 2021. Participants had nasal specimen and survey data collected in a repeated cross-sectional manner during two types of recruitment events: routine surveillance and outbreak testing for SARS-CoV-2. Individual participants were not followed longitudinally, but eligible individuals may have multiple encounters throughout the study period as routine testing was used as a study recruitment tool and proactive public health strategy. Among 12,915 collected nasal specimens from 2,930 unique participants, we observed 4.74 (95% CI 4.00 – 5.58) SARS-CoV-2 infections per 100 individuals at risk (residents: 4.96, 95% CI 4.12 – 5.91; staff: 3.86, 95% CI 2.43 – 5.79) were identified. Most infections were asymptomatic at the time of detection (74%) and detected during routine surveillance (73%); however, outbreak testing yielded higher test positivity compared to routine surveillance (2.7% vs. 0.9%). Among those infected, residents were less likely to report symptoms than staff. Participants that received that season’s influenza vaccine and were current smokers had significantly lower odds of having an infection detected. Furthermore, we found that from 11/1/2020 – 2/28/2021, a total of 969 unique staff (n=297) and residents (n=672) participated and provided 3,966 survey responses regarding COVID-19 vaccination intent and uptake. Among residents, 53.7% were vaccine accepting, 28.1% reluctant, 17.6% deliberative, and 0.6% already vaccinated, whereas among staff, 56.2% were vaccine accepting, 14.1% were reluctant, 16.5% were deliberative, and 13.1% already vaccinated at their last survey. We observed higher odds of vaccine deliberation or reluctance among Black/African American individuals, those who did not receive a seasonal influenza vaccine, and those with lower educational attainment. There was no significant trend towards vaccine acceptance. Altogether, our findings provide a more nuanced understanding of SARS-CoV-2 infection burden and COVID-19 vaccine intent trends in a high-risk, underserved population. It is imperative that shelter-based routine surveillance including SARS-CoV-2 testing of all persons, regardless of symptom profile, is essential in ascertaining the true burden of SARS-CoV-2 infections among residents and staff, and that public health authorities planning vaccination campaigns in shelters take an intersectional, person-centered approach to addressing important health inequities.