A hierarchical radial tree visualizes COVID-19 case counts from a CSV dataset, organized by continent, country, and province, with leaf nodes sized by confirmed cases. The animation highlights nodes on hover by fading unrelated branches, while tooltips display case totals. Built with React and D3 v5, it uses `d3.nest()`, `d3.hierarchy()`, and `d3.cluster()` to compute the layout, with `d3.line()` drawing links and a viridis scale coloring nodes by depth.