The graphics below are intended to supplement the many useful charts and maps on the official Utah Department of Health web site. The data come from the UDOH site and from UDOH data archived by the COVID Tracking Project and by Robert Gehrke of the Salt Lake Tribune.
All dates on this page correspond to when the information was first reported to the public on the UDOH web site. The charts on this page may therefore differ from charts on the UDOH site, most of which back-date the data to the date when the test was performed, the diagnosis was made, or the hospitalization or death occurred. Both methods of plotting the data have their advantages. The advantage of the charts on this page is that they allow consistent comparisons of the latest daily updates to past trends in those same daily updates.
For further information: To see how Utah compares to other states according to a variety of COVID-19 measures, check out the map and tables at covidexitstrategy.org. Wikipedia has a useful timeline of how the pandemic has played out in Utah, and of the measures taken to combat it.
The solid curves show the 7-day averages, to smooth over daily fluctuations and weekend reporting lags. Each average is over the date shown and the six previous dates.
Note: On July 16 the UDOH site began displaying the number of “total tests reported” alongside the number of “people tested”. These numbers are different because many people have been tested more than once. I have modified the title of the first chart below to clarify that it shows the number of people tested.
|Cumulative||Last 7 days|
|Confirmed cases per person tested|
|Hospitalizations per confirmed case|
|Deaths per confirmed case|
The coronavirus pandemic has affected Utah’s different regions unequally. To see these variations at a broad scale we can look at the confirmed case numbers for Utah’s 13 health districts, each of which consists of one or more counties.
You can use the following interactive map to display the district-level case numbers in a variety of ways. Click or tap on a district to see that district’s data. Note that the map does not show the large variations that can occur within a district; some of the maps at the UDOH site do a good job at that. The population estimates are from the U.S. Census Bureau, for the year 2019.
The following bar chart shows the same data as on the map above, but omits the geographic information while making it easier to quantitatively compare districts.
Per million residents
The next two charts make it easier to see the trends. The first shows the absolute case numbers by district and date, with a 7-day average (the black line) for the sum of all districts shown. The second chart puts the 7-day averages on a per-capita basis (actually per million residents). Use the checkboxes to select which districts to include in these two charts.
|Bear River||San Juan County||Summit County||Utah County|
|Central Utah||Southeast Utah||Tooele County||Wasatch County|
|Davis County||Southwest Utah||TriCounty||Weber-Morgan|
|Salt Lake County||7-day/statewide avg.|
(Please note that this addendum has not been updated since May 26, 2020.)
It is reasonable to wonder whether comparing the numbers of confirmed cases across districts gives an accurate picture, when testing for the virus may be more available in some districts than others. (This is a major issue when comparing states or countries.) Could it be that the low numbers of confirmed cases per capita in most of Utah's rural areas are partly or entirely the result of a shortage of testing there? The major outbreaks in the Navajo Nation and the Logan-Hyrum area have shown that testing can be slow to reach disadvantaged sub-populations. On longer time scales, however, there seems to be no shortage of testing in Utah’s rural districts.
The UDOH web site does not provide district-level testing numbers, but seven of the districts (including the five largest ones) provide these numbers on their own web sites. Here are the available data as of May 26, 2020:
|Salt Lake County||79,674||4,632||0.058|
(I calculated the last row from the first seven and the state-wide numbers.) Tentatively, then, it appears that testing is widely available (at least by U.S. standards) across the state of Utah. Furthermore, the percentage of positive tests seems to be directly correlated with the number of cases (or the population density), suggesting that further testing would turn up more cases in those areas that already have the most confirmed cases (and hence increase the disparities displayed in the charts above). It is unfortunate, though, that we don’t have district-level testing numbers for the three districts that have (as of May 26) the highest per-capita rates of confirmed cases.
As a further check, we can use data from the UDOH web site to compare district-level hospitalization rates. A higher ratio of hospitalizations to confirmed cases could be an indication that more mildly symptomatic cases are going undetected.
As of May 26, the cumulative state-wide hospitalization rate is 0.081 (hospitalizations per confirmed case). The district-level rates vary from this value, but we would expect these data to be noisy, especially for the smaller districts. In the chart below I’ve compared the district-level rates to the approximate range that we would expect, given the limited statistics, if each person confirmed to have the virus had the same (independent) probability of being hospitalized. (Technically, the displayed range is two standard deviations to either side of the state-wide average.)
The fact that no district has a hospitalization rate above the expected range suggests again that testing is widely available throughout Utah, with plenty of mildly symptomatic cases being included in the data for every district. The only discrepancy that might be statistically significant is in Utah County, where the hospitalization rate is unexpectedly low (yet we know that Utah County’s positive test rate is slightly above the state average). Salt Lake County’s hospitalization rate and positive test rate are both somewhat on the high side, so it seems likely that further testing there would turn up more mildly symptomatic cases.
This web page created by Dan Schroeder, Physics Department, Weber State University. Feel free to copy and share. Use your browser to view the source code, numerical data, and open-source (MIT) license. I am grateful to Weber State University for hosting this web page and for supporting faculty scholarship in many other ways, but readers should understand that this is a project of an individual faculty member, and that neither Weber State University nor the Physics Department is responsible for the content of this page.