Trends

Trend Heatmaps

The first trend heatmaps displays the weekly percent change in viral load at each wastewater treatment plant relative to the week prior. In short, this is the week-to-week percent change in viral load.

Here is an example of how to read the heatmap. The arrow is hovering over a square on the heatmap corresponding to Northgate WWTP on November 7, 2022. At Northgate, on October 31, 2022 the viral load was 11.759 log10 copies/day and one week later, on November 7, 2022 it was 11.864 log10 copies/day. The week-to-week difference is 0.105. Therefore the percent change in viral load relative to the October 31, 2022 viral load was 0.89%. The viral load figures for this heatmap were converted to the log10 scale for plotting purposes.

If you hover over a square on the heatmap, a box will pop-up to show the WWTP, date, and weekly relative percent change for that square

The second trend heatmaps displays the weekly viral load as percent of the benchmark levels change at each wastewater treatment plant.

Here is an example of how to read the heatmap. The arrow is hovering over a square on the heatmap corresponding to Northgate WWTP on November 7, 2022. On the benchmark date, July 6, 2020, the viral load at Northgate was 6.289e+11 copies/day and on November 7, 2022 the viral load was 7.310e+11 copies/day therefore on November 7, 2022 the viral load was at 116% of the July 6th viral load amount. For plotting purposes, the color scale is in the log10 scale.

If you hover over a square on the heatmap, a box will pop-up to show the WWTP, date, and percent of benchmark levels for that square

Wastewater and Other Metrics

There are two plots that display the wastewater viral load data alongside four other COVID-19 metrics. The metrics in the plot are:

• Wastewater Viral Load for the City (Dashed Magenta line)

• 7-day average Positivity Rate (Green line)

  • Green dashed Positivity Rate indicates that these dates do not have complete data

• 7-day average Emergency Department (ED) Visit Rate (Purple line)

• 7-day average General Bed Rate (Light Blue line)

• 7-day average ICU Bed Rate (Dark Blue lines)

One plot displays the data since September 2020 and the second plot displays the data from the past 6 months. The below figure gives an example of the relationship between the two plots.

The orange box is the data displayed in the "Wastewater and Other Metrics (Recent)" plot

Data Sources:

• Positivity Rate: Houston Health Department (HHD)

• Emergency Department (ED) visits: Houston Health Department ESSENCE

• General Bed and ICU Bed usage: SETRAC, Harris County