This example visualizes the relationship between age and BMI in insured individuals using a horizontal bar chart, displaying the top 15 counties by the number of hospitalized COVID-confirmed patients. The chart uses an SVG rendering with React for state management and D3 v5 for scales, axes, and data loading. Specifically, it employs `scaleBand` for the y-axis counties and `scaleLinear` for the x-axis patient counts, with data fetched via `d3.csv` from a GitHub raw URL. The bars are drawn as SVG `<rect>` elements, and custom tick labels replace traditional axes for clarity.