Data Notes for the Week of September 10
posted
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 more than doubled since last week.
Cases per day ranged from 36 to 195 with an average of 94 cases per day. Last week’s average number of cases per day was 45. In this 14-day period there were 1,321 total cases:
- Of all 1,321 cases, 537 (41%) were tested at community testing sites, 546 (41%) were tested by University Health Services, and 28% were tested in a healthcare setting.
- Of 1,213 people who have been fully interviewed so far, 388 (32%) reported attending a gathering or party with people outside of their household.
- Of 1,213 people fully interviewed so far, 753 (62%) identified the likely source of infection as close contact with another lab-confirmed COVID-19 case.
- Of 1,213 people fully interviewed so far, 493 (41%) were associated with a cluster: 428 from college-aged housing, 11 from college sports teams, 14 from workplaces, 10 from congregate facilities, 10 from childcare facilities, 9 from bars and restaurants, and 6 from weddings that took place outside of Dane County.
- Of the 10 cases from childcare facilities, 2 were children and 8 were adults.
- Of the 14 cases from workplaces, 2 cases were from more public-facing workplaces and 12 were from less public-facing businesses.
UW-Madison students and staff make up 65% of Dane County cases.
During this 14-day period, 846 UW students and 10 staff (856 total) tested positive, making up 65% of our total cases.
Of the 856 UW cases in this 14-day period:
- 546 (64%) were tested by UHS, 246 (29%) were tested at the Alliant Energy Center, and 64 (7%) were tested at other sites.
- 828 (98%) were between the ages of 18-22.
- 441 (52%) were associated with a cluster: 426 from college-aged housing (including sororities, fraternities, dorms, near-campus apartments), 17 from UW sports teams, 2 from congregate living facilities, and 2 from a gathering. Note that these categories are not mutually exclusive, and some students were associated with more than one cluster.
Three key strategies are in effect to help slow the spread of the virus. On September 4, we issued quarantine notices to over 400 UW fraternity and sorority members due to outbreaks within their chapter houses. On September 7, UW directed undergraduate students to restrict movement for 14 days, and on September 9, UW shifted to two weeks of remote instruction and placed two residence halls under quarantine. Strategies to restrict movement and reduce contact over fourteen days have been effective in slowing the spread of disease in other communities, but keep in mind we will not see the effects of this intervention immediately given the incubation period of the virus.
The target for grades 3-5 was not met this week.
The K-12 school metrics are detailed on our website. K-2 is currently open, having met its target. We are continuously reviewing outbreak data, and the decision to end in-person instruction will be determined based on several factors, including but not limited to number of positive cases, extent of exposure, and contact tracing capacity. Because this case increase is concentrated among UW students with little evidence of spill over into other parts of the community, we do not plan to end in-person instruction for students in grades K-2 at this time.
|
Grade levels |
Target for Possibly Resuming In-Person Pupil Instruction |
Status |
|---|---|---|
|
K-2 |
A 14-day average of 54 or fewer cases per day, sustained for four weeks |
Met on August 18, may open per Emergency Order #9 |
|
3-5 |
A 14-day average of 39 or fewer cases per day, sustained for four weeks |
Not met |
|
6-12 |
A 14-day average of 19 or fewer cases per day, sustained for four weeks |
Not met |
The community spread metric declined this week.
About a third of people with COVID-19 do not know where they could have been exposed, down from 40% last week. A high percent of cases who don’t know how they got sick means there likely are people unknowingly spreading the virus in the community.
The lab timeliness and contact tracing metric declined and turned 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. During this period 55% of cases were contacted by public health within 48 hours of being tested, compared to 73% from our last snapshot. This two-week period saw the highest number of tests per day in the pandemic thus far—3,181. At the end of August, over 90% of lab specimens had a result within 24 hours of collection. Today, that percentage is closer to 40.
For the 12th week in a row, Dane County is classified as “high activity level” on the Wisconsin Department of Health Services (DHS) COVID-19 Activity Level Tracker.
Our Forward Dane metric for cases (see the first section of this blog) accounts for burden but not trajectory. The DHS metric combines the burden of cases over a two-week period (number of cases per 100,000 residents) and the trajectory, which measures the percent change in cases from the previous week to the current week and whether that change is statistically significant.
As of the DHS update on 9/9/20, Dane County has a high burden of 242 cases per 100,000 residents, and a growing trajectory in the number of cases from the most recent 7-day period compared to the prior 7-day period. This puts us at a high activity level. We want to reduce our activity level in order to better control the spread of COVID-19 in our community.