A dual-axis bar chart compares varicella vaccination and case rates across five South American countries in 2020, using a CSV dataset. The visualization is built with React and D3 v7, combining `scaleBand` and `scaleLinear` for positioning. The same chart includes interactive bars that toggle a country's highlight, a rotated x-axis for country labels, and a title rendered in Spanish, all coordinated through a custom `main` function and React state.