The fraction of each virus's confirmed inpatients who are in the ICU — a proxy for how severe the hospitalized cases are. Small-numerator states swing month to month. Grey = no reporting that month. Hospital reporting was voluntary before it became mandatory on Nov 1 2024 (and RSV/flu were added after COVID), so earlier months have thinner coverage. The colour scale is fixed per series across all months, so colours are comparable as you slide through time.