To Any Reader:
I hope you can help me clarify the Governor’s most recent directives for Washoe County and
the data he’s used and will use going forward to update his directives.
As a strong supporter of making data-driven decisions, I really, really agree with the Governor’s
decision to return to the guidelines before July 10th, 2020 for each county, if and only if, specific
quantitative thresholds are reached.
Yet, I’m struggling to calculate the metrics below as of July 10 and how far we need to go to
move beyond these four thresholds in Washoe: <150, > 100, > 25, and > 7%.
Could you ask whoever understands these metrics to provide these four values as of July 10?
“…Counties were identified if they had "elevated disease transmission" if they met at least two of three criteria:
1. Average number of tests per day (per 100,000) < 150. The average number of cases resulted during the previous week in a county, divided by the number of people living in the county. This number is then multiplied by 100,000 to control for varying populations in counties.
2. Case rate (per 100,000) >100. The total number of cases diagnosed and reported over a 14-day period divided by the number of people living in the county. This number is then multiplied
by 100,000 to control for varying populations in counties.
3. Case rate (per 100,000) > 25 AND testing positivity > 7.0%. The total number of positive
polymerase chain reaction (PCR) tests divided by the total number of PCR tests conducted. This
number is then multiplied by 100 to get a percentage. Due to reporting delay (which may be
different between positive and negative tests), there is a 7-day lag…”
The following are the historical values I’m using to frame my questions below:
Assuming:
- 471,519 population of Washoe County, as estimated by the Census on July 1, 2019
- 328,239,523 population of the US, as estimated by the Census on July 1, 2019
As of July 10, according to Washoe’s Regional Information Center, there were
- 3,507 Total Cases
- 743.8 Cases per 100,000 People
- 48 Moving Average of the past 14 days of Daily New Cases
- 1,031 Moving Average of the past 7 days of Tests Per Day
- 218.6 Moving Average of the past 7 days of Tests Per Day per 100,000
As of July 10, according to the CDC, in the US, there were
- 3,106,931 Total Cases
- 947.9 Cases per 100,000 People
As of July 10, Washoe is now 78% of the national Cases per 100,000. This is way up from
approximately 30% during our lock down.
My questions:
1. Threshold #1 is “Average number of tests per day (per 100,000) < 150”. According to
above: Moving Average of the past 7 days of Tests Per Day per 100,000 as of July 10 is
218.6. Why does it make sense for this value to go down?
2. For threshold #2, how do I calculate and determine when the “Case rate (per 100,000)
>100” and for threshold #3 when the “Case rate (per 100,000) > 25”.
3. The #3 thresholds include a “testing positivity > 7.0%”. If I assume this is calculated as a
7-day moving average, as of July 10, Washoe’s rate was 5.9%, way below the very recent
peak of 12.2% on June 30. At first this sounds great. However, the Moving Average of
the past 7 days of Tests Per Day on July 10 was 1,051, down 46% from 563 on June 30. I
suspect the case threshold in #3 adjusts for this, yet how is this calculated. Also, why
have the Tests Per Day dropped so precipitously?
On April 29, a Washoe Health Department spokesman said testing “…could be increased, if
need be, up to 1800 a day using two shifts…”.
On July 10, The New York Times reported the State of Nevada’s testing rate was only 24% of the
“…level considered necessary to mitigate the spread of the virus…” using the methodology of
Harvard Global Health Institute.
The national average was 39%, 15 states were over 100%. As has been true since the beginning
of the lock down, New York’s horrible death rate drove them to fight COVID-19 with a laser
focus. New York is now testing at a way above average rate of 236%, driving down their positive
test rate to 1%.
It’s unclear to me what time period they used. The article reported Nevada had an 11% positive
test rate at the same time.
Let’s avoid blaming individuals. Why as an entire community are we so inadequate in fighting COVID-19 compared to so many other states and countries around the planet?
I realize these are questions best answered by some combination of Washoe staff and epidemiologists advising the Governor. I know they are inundated by requests from the media and amateur number crunchers like me. That’s why I’m asking for help from anyone reading this post or anyone referred by her. Hopefully, these answers could also be publicized by the media and explained to the mainstream public.
Thanks so much.
Gordon Gossage
Regenesis Reno, Inc.
gordongossage@gmail.com