David Salzberg's Analysis of the COVID numbers for Virginia, focusing on Northern Virginia.
Subscribe to this blog
Follow by Email
Virginia COVID-19 Status for Sept 10
Get link
Facebook
Twitter
Pinterest
Email
Other Apps
Daily Status, Sept. 10
Reminder: any sections that are unchanged since yesterday are grayed out.
The following is a rant. It probably should be in the COMMENTARY section, but I feel the need to put it up here. I am often asked why I do this. I talk in general terms about reporting, etc. But a news story yesterday shows why: I do not trust the government to give an accurate assessment. The intentional downplaying of the risks and numbers means that people like me have to dig into the numbers to figure out what is happening.
Summary/Situational Awareness
It looks like some colleges are either getting a handle on the virus or achieved herd immunity: Radford and VCU are stable now. Unfortunately, the outbreak at JMU continues to spread. And VT is starting to spiral out of control.
Across the commonwealth of Virginia, there were 1236 reported new cases of COVID-19. The number higher than the recent trends, and is more than 1 standard deviation above the mean. This probably is because of the cases which were not reported on Sun-Tues. Overall, cases are essentially flat for the last three weeks. It is worth noting that, over the past three weeks, 14% of the positives have been from colleges; today, colleges account for 15% (181) of the cases are directly related to college; without the college cases, the numbers would be decreasing by 1%/day Regionally, only SW and NW VA is increasing, largely the result of the outbreak at Radford, VT, and JMU. The testing numbers across the state remain ok, but not great, at around 7% positive. I would like to see the overall positive rate under 5%
Outside of college towns and a few smaller cities/towns, the state is doing well. In fact over the last three weeks, 14% of the probable active COVID cases are affiliated with a the colleges of Radford, JMU, VT, UVA, and VCU; those colleges account for 1.5% of the population.
Regions:
We have completed the tradition from COVID-19 being an urban disease to being a rural disease. The urban centers of NOVA and Hampton Roads are showing the lowest infection rates whereas the highest rates are in the rural SW and NW parts of the state. Though, in those regions, the growth is largely driven by three colleges: JMU, Radford, and VT.
Regional growth rates are (in fraction per day) are primarily impacted by anomalously low case numbers the last two days, probably the result of the holiday.
NOVA: .990 -- GMU
Central VA: .996 -- UVA & VCU
Hampton Roads/Eastern VA: .963-- W&M, CNU & ODU
SW VA: 1007 -- VT & Radford
NW VA: 1.013-- JMU
The state as a whole is is increasing at 1.002.
Daily case count per 100,000 is a often sited metric (below 10 (0.01%) statewide would take VA off the quarantine list . The following table shows the number per region.
Daily Cases/100,000
(corrected for testing)
Region
Last month
Last week
NOVA
9.6
8.7
Eastern
12.0
8.8
Central
12.2
11.5
NW
9.1
16.3
SW
14.7
18.1
The following charts are for the 5 regions/trends. For the last month or so, we note that NOVA have been flat at around 300 cases per day, Hampton Roads (Eastern) drummed from about 800 to under 300 .Again, SW VA, even with the lower population, has mother-in-law same number of cases than any other region. As expected, the extreme downward trend present in the last several days was the the result of the low weekend case count.
Local/Northern VA:
Northern VA has returned to the trend; the low case counts were, as expected the result of the holiday weekend.
Currently, every Northern Virginia jurisdiction is showing a decrease.
Fairfax Co.: 0.989
Arlington Co.: 0.967
City of Alexandria: 0.989
Prince William Co.: 0.988
Loudoun Co.: 0.996
The growth rate is defined as Rt, or the growth time constant. Simply, todays number are approximately the growth rate times yesterday's numbers. This is the exponential time constant. Fortunately, the time constants are about 1, and our rate of cases is about 7/100,000 per day. Ideally, we would be 0, but 7 is much better than our peak in which was around 30/100000K.
About 14 day ago, Arlington began enforcing social distancing guidelines. Since then, there trend has gone from 1% per day to -5% per day. Now, Arlington is doing the best; Alexandria and PW are doing worse.
What is most noteworthy of the NOVA Zip code map is the the overall lack of contrast. With the exception of near zero population localities, every part is doing about the same.
Northern VA overall is down a bit, with the notable exception of Vienna which is seeing a 50% increase is cases over the last week. Vienna is still below the statewide average, but Vienna is trending in the wrong direction.
Region
Last month
Last week
Fairfax Co
Vienna
4.6
8.8
McLean
4.7
6.5
So. Alexandria
12.0
9.2
Reston/Herndon
9.5
7.4
Annadale/Fall Church
12.5
10.2
Fairfaix
8.0
5.5
Arlington/Alexandria
No. Arlington
8.1
4.9
So. Arlington
13.2
9.3
Alexandria City
14.4
12.8
Note that the current up trend in Vienna is concerning; It is also possible that some college students listed the home address with off-campus covid tests, but that should be effecting other parts of the regions in a similar manner.
Age Distribution:
The trends/growth for the the middle aged gas dropped to be similar to the teen/tween and elderly. If we look at state-wide numbers, we see a very different trend set: all ages are doing well except those that include college ages (18-24). As we can see, NOVA flollows the growth trend of the state, except for teens/tweens. I am confident that growth is driven by students at college.
<10 0-19. 20-39. 39-59. 60+
NOVA 1.00 1.01 0.99 0.98 0.99
AllVA 0.99 1.03 1.00 0.99 1.00
Unfortunately, I can not parse out 18-24 separate from the other groups.
Note that the reported numbers were low at all colleges yesterday. I suspect this was related to the reporting being in the middle of the long weekend. I am not changing anything other than the tables and charts based on today's numbers.
My process combines the VA Department of Health data and what is reported by the colleges. The report is as of 11:00 AM ET.
RED means there is clear evidence for community spread
YELLOW means there may be community spread; still ambigious
GREEN means no evidence of community spread
BLACK means they went online.
College
% Positive
VDH Cases*
Estimates Cases**
Dashboard Cases
% of population infected ***
Va Tech
18.2
654
2385
587
7.0
GMU
3.0
18
18
16
0.1
UVA
12.7
155
394
214
1.7
ODU
6.0
0
0
16*****
0
JMU
42.8
909
>2000
1136
>10%
CNU
9.6
0
0
4******
0.000
UMW
63
0
0
N/A
0.000
Radford
67.1
497
>1000
357*****
>10%
VCU
1.05
136
287
197
0.9
W&M
1.3
0
0
<10
0.000
** estimated number of cases is an attempt to normalize for testing limitations. Specifically, I assume at 5% positive, 100% of the cases would be caught. so I normalize it to that value. If the % positive is very high (>40%) I am likely overestimating the numbers.
*** Dashboard cases are only counted if I can find the dashboard. In some cases, it is difficult to distinguish positive tests from cases (1 case may have multiple positive tests; that is mostly at VT). I include active cases if reported, otherwise, I use total cases.
****% population uses the total reported number of students rather than just those on campus; it may be off when the percent positive is above >40%.
The numbers of new cases at Radford seems to have peaked. We do not know how many people have/had the disease. Because the percent positive remains as high as it is, though, most of the people who need to be tested might not be able to be tests (or at least might not have been able to get tested in the last several weeks). The number of new cases is high, but not growing -- and possibly shrinking. At this point, my only recommendation is to perform serology/antibody studies to retrospectively determine the number of cases. Radford tested the students prior to arrival, but allowed students on campus prior to the test results.
JMU is going online. JMU has been fairly transparent with the situation, but could not get ahead of it. At this point, it is mitigation. They sent the healthy students home, and are allowing the positive to stay on campus, which is critical for society as a whole There are now multiple hospitalizations in Harrisonburg that are of the age group expected for College students. JMU did not require testing prior to arrival on campus.
We have seen the prevalence of the virus in Blacksburg increase with the return of the students. Each day, there are 30-60 new cases validated. The most concerning aspect of Va Tech is 18% of the tests are coming back positive. That suggests that either they are rationing tests, or they are undercounting. Either way, I estimate indicate more than 5% of the student body is positive. Short of a two week pause, I am not sure how Tech will contain the spread. VT claims there is no uncontrolled community spread, but the data does not support that assertion. Virginia Tech tested only on-campus students.
With the students return, there has been a marked increase in cases. It appears there is community spread. And it is growing, but relatively slowly. large scale community spread, if it occurred, should show up in the next several days Between the increase in the percent positive and the absolute numbers increasing, UVA is trending in the wrong direction. UVA tested all students prior to arrival on campus.
VCU seems to have the virus under control -- it was promoted from RED to YELLOW. The numbers have shown no significant increase in the last several days; quarantine and isolation space is becoming more prevalent. Being in an urban setting the zip-code and regional surveillance that works well at some of the other schools is not particularly helpful here. So, I have to rely on the dashboard.
Other schools:
William & Mary -- so far so good -- No evidence of community spread. There are now cases on campus (I think). I am assuming they have somewhere between 1 and 9 cases; looking at the numbers for Williamsburg, it is probably 1 or 2. It is worth noting that pre-arrival testing has identified 20 cases, which were not allowed on campus. W&M will retest all students next week. W&M tested all students prior to arrival in town.
CNU -- Students have been back upto 1 month. A few cases. Under control.
ODU -- Nothing noteworth. My concern with ODU is they did not test the students, so there may be asyptomatic/presymtomatic spreaders on campus (see JMU). There dashboard is a week old, which would be concerning, but the data suggests there can not be more than a 20 cases total, which is below what I can resolve because of the noise level.
UMW -- Not open yet.
GMU -- Nothing noteworthy. GMU tested all students.
Communities:
Based on the above charts, the issue is no longer the communities. The issue is the campuses. We are seeing the growth in New River (VT/Radford) and Harrisonburg. The sad thing is those communities had the lowest numbers prior to the students return.
Commentary:
I try to be apolitical in this blog, but today, I want to say: we need to demand honesty from our national leadership with the pandemic. When our leaders are talking about "not panicking the people" what they are saying is we unable to make informed decisions about the disease or other things.
Also, Masks are our friends. Masks significantly reduce the risk of disease transmission, if they are worn correctly. The purpose of masks are 1) to contain any virus you may discharge through breathing, talking, coughing or sneezing, and 2) to protect you from incoming viruses with your breathing. In order for the mask to function, it must cover the mouth and nostrils. The chin and neck do not need protection (unless you have a tracheotomy). I am seeing too many people with the nose and/or mouth exposed. And I have even seen town employees with the masks that way. Confronting does not seem to work, except sometimes with a neck mask, people just forgot to put it on. It is not enough to have a mask; it most be worn properly. WHO put the following graphic:
I try to keep my political biases out of it. Unfortunately, some politicians have turned data into a political issue. Yesterday, while driving home, I heard a prominent politician state that the America's numbers would be much better if we excluded NY. I am not sure when the quote was captured. But, I am a data and science person; based on that, I wonder how policy can follow when data is fabricated. The data for cases in the USA, with and without NY are shown below. In April, our cases there about 50% NY, since then NY has been doing better. Since June 1, NY has accounted for 1.5% of the cases nationally, even though it has 5.8% of the population. So, currently, NY is outperforming the country. Even including the early days, NY is at 7.2% the cumulative cases, about 25% higher than you would expect. By comparison, Florida accounts for 10.2% of the cases but 6.3% of the population. And FL should have known better. (VA is at 2% of all cases, and 2.5% of the population).
The numbers do not lie.
Attribution:
1) You can repost / share in the entirety by forwarding the link, 2) If you want share partial content, you must receive my permission – I need to make sure you understand what I am saying. If anyone sees this work being used without attribution, please let me know as soon as possible. I am willing to have an informed discussion / debate on my approach, but I want to make sure the proper context is captured.
Daily Status, August 29: Today's report was late because the data are late. Typically, I report 1-2 hours after the data are published. Note: Today, I focused on the colleges. Much of the text in other sections could be reused. The figures are 100% from today, though. Summary/Situational Awareness Like yesterday, today's concern are with the universities. Only two (W & M aare showing no increase since the students arrived. Va Tech and UVA are showing increases, but probably consistent with the increased populations -- they have moved to monitor closely. Meanwhile, there is large scale community spread at JMU, Radford and possibly VCU. More on this in the section title "Colleges". The discussion of colleges will take up most of the new discussion Across the commonwealth, there were about 1217 reported new cases (including Radford). This with is slightly above the average number of cases in the last three week, but within 1 standard deviation. Regionall
Daily Status, Nov 8 Reminder: Any sections that are unchanged since yesterday are grayed out. Please be kind. I have been putting out a daily update since March. As you may have noticed, I had not put one in 10 days. I am trying to get this one out, but my energy level is low. I spent half of the last 10 days in the hospital, and had multiple procedures to fix the acute issues (bile duct blockage) so I can address the longer term issues of fighting off the cancer which is growing inside of my body. I had started working with an editor to improve the quality of the writing, but I am going to forgo that, as the process takes time, and I can not be assured that I will have the energy to complete the writing at that time. I am not sure how much longer I can keep this up. I remain concerned that the media does not understand the math well enough to accurately report the situation. However, I am confident that, on Jan 20 at 12:00 noon, the excellent and dedicated government
Daily Status, October 21 Reminder: any sections that are unchanged since yesterday are grayed out. I try to update this every day between 11:00 and 12:00. However, my updates are based on when the Virginia Department of Health updates; it takes some time in analyze and collate the data. In addition, because I my own health issues, there will be days when the update is late or does not happen. The one thing to remember is the day-to-day changes are minor. Any trend takes several days to identify, and I will be looking at the data daily (that is easy), but may not update the blog. One thing that is immensely personal to me is I need to avoid COVID-19. Like, I do not know my mortality risk exactly, but last week, I thought my Infection mortality rate was 5-10%. With active cancer, that doubles, to 10-20%. So if you see me in town, wear a mask. I try to avoid challenging people, but maybe it is time. If I can see your nostrils, you are not wearing it right. If I can see a ga
Comments
Post a Comment