Coronavirus Contextualized, 34th edition: Case, test positivity growth may be plateauing, though too early to tell
Welcome to the 34th installment of “Coronavirus Contextualized,” a recurring feature in which we explore some of the numbers swirling around in the time of coronavirus.
Through these stories, we hope to parse the numbers, including confirmed cases of COVID-19, people tested, number of hospitalizations and deaths, and provide some context to them. You can view the prior editions of “Coronavirus Contextualized” here on our coronavirus page.
These stories serve as a written roundup of the COVID-19 trends we kept our eyes on this week, with all graphs and charts living permanently on our COVID-19 data page, where they are updated multiple times a day with the latest numbers.
We’re continuing to take suggestions for what kind of data, graphs and trends you would like to see analyzed in future versions of this story or included in a future update of our data page. Reach out to [email protected] with any feedback.
Below, we take a look at the latest COVID-19 trends in Nevada more than nine months since the state’s first confirmed case was reported and as health care workers started receiving the vaccine this week.
However, state officials on Thursday announced that Nevada's second allocation of Pfizer's COVID-19 vaccine had been cut by 42 percent. Other states reported having their vaccine allotments slashed, too, as senior Trump administration officials characterized the cuts as a misunderstanding.
Still, Gov. Steve Sisolak, in a statement, criticized the move from the federal government.
"States need clear and precise updates and information from the federal government as we continue the large and complex process of distributing this critical COVID-19 vaccine across the nation and here in Nevada," Sisolak said. "To slash allocations for States – without any explanation whatsoever – is disruptive and baffling."
As a note, this is the last “Coronavirus Contextualized” of 2020. Thank you so much for following along with us this year, and we’ll see you on Jan. 8 for our first edition of 2021.
Cases and test positivity
While it appears the number of new reported daily COVID-19 cases in Nevada may be stabilizing or even starting to decrease, it’s too early to know whether this is the start of a sustained trend or a short-term fluctuation in the data — and case numbers still remain high.
An average of 2,512 new COVID-19 cases were reported each day over the last seven days as of Thursday, down from a record average of 2,736 last week. Both of those numbers are, however, still more than double the previous record, 1,176, from the summer, the last time COVID-19 cases surged.
“While we are experiencing something that looks like stabilization, or a potential towards a trend, a stabilisation trend, or even a downward trend in some parts of the state, we're still highly elevated, and we could very easily start trending back upwards here in the near term as well,” said Caleb Cage, Nevada’s COVID-19 response director, at a meeting of the COVID-19 Mitigation and Management Task Force on Thursday.
Cases have been rising since mid-September, when a low of 267 cases on average were reported each day.
Since the beginning of the pandemic in March, there have been 197,132 COVID-19 cases reported statewide. More than a third of those cases, 73,036, have been diagnosed in the last month, and 9 percent, or 17,587 cases, have been reported in the last week.
One in 16 Nevadans has tested positive for the virus since the beginning of the pandemic. Nevada ranks 17th in the nation for COVID-19 cases per capita.
Nevada’s test positivity rate — which looks at the percentage of tests or people coming back positive out of the total tested — has similarly started to stabilize, or even decrease. As usual, we’ll look at two different methods of calculating test positivity below, using both individual people and a metric known as testing encounters.
Starting with the number of new reported people who tested positive for COVID-19 out of the total number of new reported people tested each day, the state’s seven-day average test positivity rate was about 41.5 percent as of Thursday, down from a recent high of 45.9 percent on Sunday. The most recent low point, before the surge this fall, was 9.2 percent on Sept. 17.
There are, however, some drawbacks to looking at test positivity using individual people since some people are tested repeatedly. For instance, someone who tested negative four times but tested positive on their fifth time would be counted as a new positive person but not a new person tested. (In other words, they would be counted in the numerator but not the denominator.)
Additionally, someone may receive a rapid antigen test that comes back negative the same day, only to have a positive molecular PCR test, which is more accurate in determining whether someone is negative for COVID-19, come back positive several days later. In that instance, the individual would be counted as a new person tested the day of their first, negative test but a positive several days later.
Another way of looking at test positivity, as we have noted each week, is to examine test encounters, or the number of individual people tested each day. This method of looking at test positivity excludes duplicate samples collected the same day but accounts for people who are tested repeatedly on different days.
It is not possible to independently calculate the test positivity rate based on test encounters because the state only reports the number of positive cases, not the number of positive test encounters. However, the state does provide this number, calculated as an average over a 14-day period with a seven-day lag. As of Wednesday, that number was 20.6 percent, down from a recent high of 21.8 percent on Dec. 8. The recent low, 6.2 percent, was on Sept. 17.
Whichever calculation you use to look at test positivity, the trends are the same. Test positivity has been generally increasing since mid-September, though Nevada is now starting to see some decreases.
At the task force’s meeting, Kyra Morgan, state biostatistician, urged caution, though, when looking at the decreases in the test positivity data.
“I just want to point out that that number is extremely high, and it's a percentage of tests, essentially coming back positive, and so it kind of has a natural glass ceiling,” Morgan said. “It naturally is going to hit a maximum and be pretty hard to be higher than a certain number. We actually have been anticipating test positivity has to start coming down because it just can't keep going up.”
Since the beginning of the pandemic, 1,090,377 people — or about one in 2.8 Nevadans — have been tested for COVID-19, and there have been 1,900,403 individual testing encounters.
Nevada is seeing record numbers of deaths reported on average each day, a trend that is finally mirroring the case growth from this fall.
The average number of new deaths each day over the last seven days was 33 on Thursday, up from 27.3 last week. Wednesday set a new record, with an average of 37.9 deaths. The previous record over the summer was 20.7.
Over the last seven days, 231 new COVID-19 deaths have been reported across the state, including:
- 159 in Clark County
- 44 in Washoe County
- 8 in Carson City
- 6 in Churchill County
- 4 each in Lyon and Elko counties
- 3 in Nye County
- 2 in Lander County
- 1 in Douglas County
In the last month, 735 deaths from COVID-19 have been reported statewide, more than a quarter of the 2,681 total COVID-19 deaths reported statewide since the beginning of the pandemic.
Churchill County still has the highest number of deaths per capita in Nevada, with 11.6 deaths per 10,000 residents, followed by Lander County at 10.8, Clark County at 9.2 and Mineral County at 8.9.
Nevada ranks 23rd in the nation for deaths per capita, up from 26th last week.
Nevada continues to see high levels of COVID-19 hospitalizations.
There were 1,975 people hospitalized with COVID-19 as of Wednesday, the last day for which data is available, up from 1,824 last week and significantly up from the recent low of 417 on Sept. 12. Nevada set a new record for hospitalizations on Sunday, 2,025, dwarfing the record set during the summer, 1,165.
However, the Nevada Hospital Association, in a report this week, said that the hospitalization curve appears to now be “flattening” on a statewide basis. The association also noted that the majority of hospital admissions remain in the 60 and over age group.
Nevada continues to have the highest number of people hospitalized per capita, 64.1 people per 100,000 residents, ahead of Arizona at 53.4 per 100,000 and Alabama at 49.5 per 100,000.
Nevada hospitals are currently staffing 6,822 beds, more than the 6,660 they are normally licensed to operate, to keep up with the demand. As of Wednesday, 83 percent of staffed hospital beds and 75 percent of ICU beds were occupied. Those numbers were 83 percent and 79 percent, respectively, in Southern Nevada and 88 percent and 62 percent, respectively, in Northern Nevada.
County by county
Sixteen of the state’s 17 counties met the state’s criteria to be flagged as at risk of elevated spread of COVID-19 as of Thursday. Storey County is the only exception.
Counties are considered at risk for elevated spread of COVID-19 if they meet two of the following three metrics:
- The average number of tests per day per 100,000, calculated over a 14-day period. If this number is less than 100, a county could be considered at risk.
- The case rate per 100,000, calculated by taking the number of cases diagnosed and reported over a 30-day period. If this number is greater than 200, a county could be considered at risk.
- The case rate per 100,000 and the test positivity rate, calculated over a 14-day period with a seven-day lag. If the case rate is greater than 50 and the test positivity rate is greater than 8.0 percent, a county could be considered at risk.
Pershing County has the highest case rate in the state at 5,702 cases per 100,000 residents over the last 30 days, followed by Carson City at 3,349 and Humboldt County at 3,100.