Impact of mRNA vaccines in curtailing SARS-CoV-2 infection and disability leave utilisation among healthcare workers during the COVID-19 pandemic: cross-sectional analysis from a tertiary healthcare system in the Greater Houston metropolitan area

ObjectivesWe provide an account of real-world effectiveness of COVID-19 vaccines among healthcare workers (HCWs) at a tertiary healthcare system and report trends in SARS-CoV-2 infections and subsequent utilisation of COVID-19-specific short-term disability leave (STDL).DesignCross-sectional study.Setting and participantsSummary data on 27 291 employees at a tertiary healthcare system in the Greater Houston metropolitan area between 15 December 2020 and 5 June 2021. The initial 12-week vaccination programme period (15 December 2020 to 6 March 2021) was defined as a rapid roll-out phase.Main outcomes and measuresAt the pandemic onset, HCW testing and surveillance was conducted where SARS-CoV-2-positive HCWs were offered STDL. Deidentified summary data of SARS-CoV-2 infections and STDL utilisation among HCWs were analysed. Prevaccination and postvaccination trends in SARS-CoV-2 positivity and STDL utilisation rates were evaluated.ResultsUpdated for 5 June 2021, 98.2% (n=26 791) of employees received a full or partial dose of one of the approved mRNA COVID-19 vaccines. The vaccination rate during the rapid roll-out phase was approximately 3700 doses/7 days. The overall mean weekly SARS-CoV-2 positivity rates among HCWs were significantly lower following vaccine roll-out (2.4%), compared with prevaccination period (11.8%, p<0.001). An accompanying 69.8% decline in STDL utilisation was also observed (315 to 95 weekly leaves). During the rapid roll-out phase, SARS-CoV-2 positivity rate among Houston Methodist HCWs declined by 84.3% (8.9% to 1.4% positivity rate), compared with a 54.7% (12.8% to 5.8% positivity rate) decline in the Houston metropolitan area.ConclusionDespite limited generalisability of regional hospital-based studies—where factors such as the emergence of viral variants and population-level vaccine penetrance may differ—accounts of robust HCW vaccination programmes provide important guidance for sustaining a critical resource to provide safe and effective care for patients with and without COVID-19 across healthcare systems.

Quantifying community resilience based on fluctuations in visits to points-of-interest derived from digital trace data

This research establishes a methodological framework for quantifying community resilience based on fluctuations in a population's activity during a natural disaster. Visits to points-of-interests (POIs) over time serve as a proxy for activities to capture the combined effects of perturbations in lifestyles, the built environment and the status of business. This study used digital trace data related to unique visits to POIs in the Houston metropolitan area during Hurricane Harvey in 2017. Resilience metrics in the form of systemic impact, duration of impact, and general resilience (GR) values were examined for the region along with their spatial distributions. The results show that certain categories, such as religious organizations and building material and supplies dealers had better resilience metrics—low systemic impact, short duration of impact, and high GR. Other categories such as medical facilities and entertainment had worse resilience metrics—high systemic impact, long duration of impact and low GR. Spatial analyses revealed that areas in the community with lower levels of resilience metrics also experienced extensive flooding. This insight demonstrates the validity of the approach proposed in this study for quantifying and analysing data for community resilience patterns using digital trace/location-intelligence data related to population activities. While this study focused on the Houston metropolitan area and only analysed one natural hazard, the same approach could be applied to other communities and disaster contexts. Such resilience metrics bring valuable insight into prioritizing resource allocation in the recovery process.

Cyclosporiasis Epidemiologically Linked to Consumption of Green Onions: Houston Metropolitan Area, August 2017

ABSTRACT During July 2017, Texas public health officials noted an increase in the number of reported cyclosporiasis cases. They detected a cluster in the Houston metropolitan area that involved four locations of a Mediterranean restaurant chain, restaurant A. A case-control study was conducted among patrons of restaurant A to identify a common food vehicle among items containing fresh produce. In matched case-control ingredient-level analyses that included both probable and confirmed cases, consumption of green onions, red onions, tomatoes, and cabbage was significantly associated with illness. A substantial percentage of case patients reported consumption of green onions, and only green onions remained statistically significantly associated with illness, whether probable and confirmed cases were included in analyses (matched odds ratio: 11.3; 95% confidence interval: 2.5 to 104.7), or only confirmed cases were included in analyses (matched odds ratio: 17.6; 95% confidence interval: 2.5 to 775.7). These results provide evidence that green onions were the likely vehicle of infection. It was not possible to trace the green onions to their source due to the need to redirect public health resources to Hurricane Harvey response efforts in Texas. HIGHLIGHTS

Racial Variation in ITP Prevalence and Rate of Chronic Disease Suggests Biological Differences

Background: Immune thrombocytopenia (ITP) is the most common cause of acquired immune platelet destruction in children. Clinical symptoms range from asymptomatic to significant and even life-threatening bleeding, fatigue, and reduced health-related quality of life. About 75% of affected children experience spontaneous remission, with the remainder developing chronic ITP. Our clinical observations suggest a decreased prevalence of ITP among Black children, although no available studies have evaluated racial or ethnic predisposition to ITP or to chronic disease. We hypothesized that biological differences in Black children alter the prevalence of ITP, relative to the general population, and may affect disease course. Methods: A retrospective analysis evaluating race and ethnicity of all children with ITP treated at Texas Children's Hospital (TCH, Houston, TX) from January 2015-July 2019 was performed, and compared to both the Houston metropolitan area and the TCH Cancer Center 2018 race and ethnicity data. Of the 699 unique patients, race and ethnicity data were unavailable for 24, and 2 patients were excluded (1 with leukemia, 1 with bone marrow failure). The remaining patients were categorized as (1) White, non-Hispanic; (2) Black, non-Hispanic; (3) Hispanic; and (4) Other. Hispanic patients included those who self-identified as (1) White, Hispanic; (2) Black, Hispanic; (3) Asian, Hispanic; (4) Multi-race, Hispanic; and (5) Unknown race, Hispanic. Demographic data was then collected in a second ITP population derived from the Children's Hospital of Philadelphia (CHOP, Philadelphia, PA) and the surrounding metropolitan area. To match the distribution reported in the Houston metro area data, a comparison was conducted focusing on the proportion of Black non-Hispanic patients in each cohort. A chi-squared test with Yates correction was utilized to compare nonparametric categorical data using GraphPad Prism version 8.0.1 for Windows, GraphPad Software, San Diego, California, USA. A p-value of &lt;0.05 was statistically significant. Results: At TCH, there were 673 evaluable ITP patients. Classifying by race only, 42 were Black (6.2%), 564 White (83.8%), and 67 Other (Asian, Mixed Race, Native American, 9.9%). There was a significantly smaller percentage of ITP patients identified as Black, non-Hispanic (n= 40, 5.9%) relative to both the Texas Children's Cancer Center (16% Black, non-Hispanic) and the Houston metropolitan area populations (16% Black, non-Hispanic, p&lt;0.0001). These data are significant given that Texas Children's Hospital sees the majority of children in the Houston metropolitan area, and the demographic data for the Cancer Center accurately reflect the Houston population (see Table). Black, non-Hispanic patients with ITP were more likely to have chronic disease (40% chronic, n=16) than the expected 20-25% in the overall pediatric ITP population. Many of the patients described as Black, non-Hispanic had secondary ITP (20.0%, n=8), most commonly due to systemic lupus erythematosus (SLE), a condition more common amongst Black patients. These findings were consistent at CHOP, with 7% of the 311 included patients classified as Black (n=22), 76% White (n=236) and 17% Other (n=54 including Asian, Middle Eastern, Mixed Race and Native American/Pacific Islander). Again, these proportions are in contrast to the general CHOP patient population (22% Black, 55.5% White and 22.5% other) and the Philadelphia metro population (42.5% Black, 41.5% White, 16% Other). The frequency of chronic ITP was also increased in Black patients in the CHOP cohort (39%, n=7). Conclusions: This analysis suggests a significant difference in the prevalence of ITP by race in children at two large tertiary care centers in the US. We found that Black children were less likely to develop ITP but those who did were more likely to develop chronic disease relative to other races. Race and ethnicity data at both institutions more closely matched their surrounding metropolitan areas, suggesting the observed differences are not due to care or access barriers. These findings support the possibility that damaging genetic variants, altered gene expression and/or other biological differences in immune response may lead to increased risk of ITP in White children, or protective factors result in reduced prevalence of ITP in Black children. Further research to explore these differences is ongoing. Figure Disclosures Lambert: CSL Behring: Consultancy; Amgen: Consultancy, Other; Bayer: Other: Ad boards; Novartis: Other: Ad boards, Research Funding; Shionogi: Consultancy; Kedrion: Consultancy; Sysmex: Consultancy; AstraZeneca: Research Funding; PDSA: Research Funding. Despotovic:Dova: Honoraria; Novartis: Research Funding; Amgen: Research Funding.

1293. Bundled HIV/Hep C testing 4 Years of Implementation at 9 Emergency Departments in the Houston Metropolitan Area

Background Individuals living with HIV infection and/or Hep C infection and unaware of their infected status are at risk of significant morbidity and a risk to public health. It has been recommended that all conscious adults presenting to Emergency Departments (EDs) be tested for HIV and increasingly testing for Hep C. Testing of all arrivals is important because a majority of both infections may not present signature signs or symptoms associated with the reason for the ED visit. For these reasons, the implementation of a bundled HIV/HepC testing protocol is reported here. Methods Data from 4 years of HIV/Hep C screening of patients 18 to 64 years old made in 9 EDs in the Houston Metropolitan Area are reviewed. Screening for HIV was using HIV fourth-generation ADVIA Centaur™ Ag/Ab COMBO (Siemens) and Hep C was tested for using Gilead Hep C Ab testing. Results During January 2013 until October 2016, 3,976 HIV/Hep C test bundles were performed. There were 40 (1.0%) HIV+ and 407 (10.2%) Hep C positive detected. Nine (0.2%) of these individuals were positive for both HIV and Hep C. A 22.5% of HIV-positive patients were co-infected with Hep C. The population had a median age of 53 years, comprising an equal number of males and females. Conclusion A significant prevalence of Hep C (10%) and HIV (1%) was found in patients presenting for any cause of major EDs in the Houston region. Bundled HIV/Hep C testing of all arrivals to EDs is an effective way to identify individuals that need to be directed to antiviral and linkage to care. Disclosures All authors: No reported disclosures.

Retrospective Dynamic Inundation Mapping of Hurricane Harvey Flooding in the Houston Metropolitan Area Using High-Resolution Modeling and High-Performance Computing

Hurricane Harvey was one of the most extreme weather events to occur in Texas, USA; there was a huge amount of urban flooding in the city of Houston and the adjoining coastal areas. In this study, we reanalyze the spatiotemporal evolution of inundation during Hurricane Harvey using high-resolution two-dimensional urban flood modeling. This study’s domain includes the bayou basins in and around the Houston metropolitan area. The flood model uses the dynamic wave method and terrain data of 10-m resolution. It is forced by radar-based quantitative precipitation estimates. To evaluate the simulated inundation, on-site photos and water level observations were used. The inundation extent and severity are estimated by combining the retrieved water depths, images collected from the impacted area, and high-resolution terrain data. The simulated maximum inundation extent, which is frequently found outside of the designated flood zones, points out the importance of capturing multi-scale hydrodynamics in the built environment under extreme rainfall for effective flood risk and emergency management.