A multi-dimensional array with PRISM
respiratory virus activity level thresholds.
Dimensions, in order, are location,
disease, and breaks.
Details
Values of disease are Influenza, COVID-19,
RSV, and ARI (acute respiratory infections).
Values of breaks are prop_very_low,
prop_low, prop_moderate, prop_high,
prop_very_high, and prop_upper_bound.
Values of location are US jurisdictions
and the United States as a whole, using
USPS two-letter codes (the values of abbr)
in us_location_table.