Data Notes For the Week of July 27
Posted on Monday, Jul. 27, 2020 at 5:45 pm
Today we released this week’s data snapshot. If you’re new to the data snapshot, we publish a weekly summary of the status for each of our metrics (you can find past issues on our data and metrics page). We have a few notes for this week’s issue:
Our average number of cases per day has decreased, but we are still experiencing high numbers of cases per day.
The number of cases per day metric was red in the last data snapshot, and it remained red during this 14-day period. Cases per day ranged from 30 to 102, with an average of 63 cases per day, down from 80 in the last snapshot.
From July 11 through July 24, 888 people tested positive for COVID-19 in Dane County. As of this morning, 736 have had complete interviews. Here’s what we know about these cases:
- Of all 888 cases, 523 (59%) were tested at community testing sites (501 at the Alliant Energy Center).
- Of all 888 cases, 273 (31%) were young adults between the ages of 18-25.
- Of 736 people who have been fully interviewed so far, 255 (35%) reported attending a gathering or party with people outside of their household.
- Of 736 people fully interviewed so far, 403 (55%) identified the likely source of infection as close contact with another lab-confirmed COVID-19 case.
- Of 736 people fully interviewed so far, 89 (12%) were associated with a cluster: 31 from workplaces, 19 from congregate facilities, 14 from bars and restaurants, 9 from childcare facilities, 6 from college-aged housing (including sororities, fraternities, near-campus apartments), 5 from in-home care services, 2 from sports teams, and 3 from other clusters.
The lab timeliness and contact tracing metric improved from the last snapshot, but is still red.
Lab timeliness (how quickly labs are reported to us) and contact tracing (how quickly we can reach out to cases) are combined into one metric because lab timeliness directly affects contact tracing. This metric has improved since the last snapshot. 52% of cases were contacted by public health within 48 hours in the last 14 days, compared to 43% from our last snapshot. While this is an improvement, this metric is still red.
As a reminder of why this metric is so ambitious, this is what has to happen in 48 hours in order to meet this metric:
- Someone has to be tested
- The sample has to be transported to the lab
- The lab has to test the sample
- The lab has to input the results in the state database
- Our team has to collect and process the result
- Our team has to call the person who tested positive
- The person who tested positive has to answer their phone when we call
We are seeing greater community spread in Dane County.
The community spread metric has turned red this snapshot—36% of people with COVID-19 did not know where they could have been exposed, compared to 30% from last week’s snapshot. A high percent of cases with no known route of disease transmission means there is likely a large number of individuals unknowingly spreading the virus in the community, which makes isolation and contact tracing much more difficult. The fact that community spread has increased even as the number of cases has decreased is somewhat concerning and is a data point that we will be watching in the coming weeks.
Percent positivity and number of tests were updated in this week’s snapshot.
Last week, we were able to create a workaround for a backlog of negative tests that was affecting our percent positivity and total number of tests.
We receive test results from labs in real time, but before they can be finalized and assigned an ID number, they sit in a “staging” area of the data system and must be manually processed by a staff member. This involves assigning a case investigator to positive tests, ensuring tests were correctly assigned to Dane County (and if not, assigning them to the proper jurisdiction), and matching tests to an individual’s record if they have already received a test and have an ID number in our system.
The backlog of negative tests became more pronounced over the past three weeks. After our spike in cases in late June, we also saw the number of tests increase by 45% from the last two weeks of June to the first two weeks of July. Our snapshot released on 7/6 did not reflect the percent positivity numbers for two days due to a backlog of tests, and our snapshot released on 7/13 did not reflect percent positivity numbers for three days. In last week’s snapshot, we did not share percent positivity or testing numbers since the negative tests had become too backlogged to provide accurate data. We then identified a method to include labs in “staging,” and on Friday 7/24 began including these tests. We will also include those numbers on our snapshots going forward, beginning today.