Home Health Care Where are the COVID-19 Hotspots? Tracking State Outbreaks

Where are the COVID-19 Hotspots? Tracking State Outbreaks

by Insuredwell
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There is growing concern about rising COVID-19 cases and other troubling trends in a subset of states that have reopened, and a few Governors and Mayors have either paused reopening or signaled their intention to do. Understanding in which states the pandemic is moving in the wrong, or right, direction, is critical but complex, as no single metric can tell the full story. For example, an increasing number of cases could be the result of more testing or the result of increasing transmission, or a combination of both.

A few existing resources examine state-level data to make assessments about current risk levels (see, in particular, https://www.covidexitstrategy.org/, https://covidactnow.org/, and https://www.aei.org/covid-2019-action-tracker/). We similarly sought to examine current trends across the U.S. and identify state “hotspots” for COVID-19. Specifically, we looked at two metrics that are readily available for all states and, when taken together, signal concern:

  • COVID-19 Cases: Percent Change in Reported Daily Cases Over the Past 14 Days. An increase in reported cases could signal a growing caseload, though it could also be the result of increased testing. Used, however, in conjunction with the change in positivity rate helps to elucidate this trend.
  • Positivity Rate: Percent Change in Share of COVID-19 Tests with Positive Results Over the Past 14 Days. The positivity rate is an important metric to monitor (the WHO recommends that it be at 5% or less). If transmission is decreasing and more people are being tested, including those who are not infected, the positivity rate should fall. On the other hand, a rising positivity rate suggests that an insufficient share of the population is being tested and/or that actual cases are increasing, and likely increasing at a faster rate than the confirmed case counts would indicate.

For each metric, we examined data from the most recent 14-day period to account for the lag between transmission and the incubation period of the virus, as well as the time at which an individual seeks and receives testing and testing results are reported to health officials; even so, it is important to note that cases from the most recent two-week period still reflect prior transmission patterns. We calculated the percent change based on a 7-day rolling average, which helps to account for fluctuations in reporting throughout each week and other noise in the data. We excluded states for which the percent change in at least one of the 14-day metrics was below 5%.

In addition to cases and positivity rates, we also include data on the percent change in the number of tests conducted, hospitalizations, and deaths, to provide additional context for interpreting trends. For example, hospitalization data provide information on severity of illness and strain on the health care system, though not all states report this information and it is a lagging measure that reflects transmissions from even longer ago. Increasing cases in the most recent period is likely predictive of future hospitalizations (and deaths), though depends on the characteristics or people being infected in any given area (since older people and those with pre-existing conditions are more likely to get severely ill once infected).

Results

Looking at the period from June 8 to June 22, 20 states are classified as hotspots (i.e., have increasing cases and increasing positivity rates over the most recent 14-day period). See Figure and Table 1 below. These states are primarily in the West (9) and South (8); three are in the Midwest. Most are states that were not hit hard earlier in the pandemic. While four of the states are reporting fewer than 40 daily cases, nine are reporting 400 or more new cases per day, and 13 states have positivity rates above the recommended WHO 5% threshold. Outside of these hotspots, an additional four states have either increasing cases or positivity rates, coupled with increasing hospitalizations and/or deaths, which could be a cause for concern.

Figure 1: States with Upward 14-Day Trends in Cases and Positivity Rates, June 8 to June 22, 2020

State 14-Day
Percent
Change in
Cases
14-Day
Percent
Change in
Positivity
Rate
14-Day
Percent
Change in
Current
Hospitalizations
14-Day
Percent
Change in
Deaths
14-Day
Percent
Change in
Tests
Daily Cases
(7-Day Rolling
Average)
Positivity Rate
(7-Day Rolling
Average)
Current
Hospitalizations
(7-Day Rolling
Average)
Daily Deaths
(7-Day Rolling
Average)
Date Stay at
Home Order
Lifted
Alabama 82.2% 28.2% 9.7% Decrease 27.3% 597.4 9.0% 653.0 9.6 April 30
Arizona 135.2% 68.0% 51.8% 9.6% 40.9% 2,536.4 21.2% 1,779.9 21.1 May 16
California 52.2% 11.9% 2.3% 2.7% 29.8% 4,148.4 4.9% 4,602.9 64.6 Still in place
Florida 183.5% 193.9% N/A Decrease Decrease 3,270.1 12.2% N/A 33.6 May 4
Georgia 63.5% 54.4% 15.5% 35.1% Decrease 1,073.4 9.7% 928.9 22.0 May 1
Hawaii 233.3% 244.1% N/A N/A 8.7% 11.4 1.2% N/A 0.0 Still in place
Idaho 144.9% 89.3% N/A 100.0% 6.9% 122.4 6.1% N/A 0.3 May 1
Kansas 77.7% 120.1% N/A Decrease Decrease 158.4 5.8% N/A 1.7 May 4
Mississippi 25.5% 38.8% 7.6% Decrease Decrease 361.4 8.8% 647.0 11.9 April 27
Missouri 26.4% 54.9% Decrease 112.8% Decrease 283.0 5.2% 489.9 11.9 May 4
Montana 316.7% 360.5% 677.8% 100.0% Decrease 17.9 1.3% 10.0 0.3 April 26
Nevada 98.7% 147.0% 2.9% Decrease Decrease 316.1 8.2% 364.1 3.4 May 29
Ohio 38.8% 6.7% Decrease Decrease 30.1% 565.9 3.9% 524.0 18.4 May 20
Oklahoma 266.6% 230.3% 29.3% Decrease 10.9% 331.0 7.3% 193.1 1.4 May 12
Oregon 103.7% 30.1% 24.9% 20.0% 79.3% 180.4 4.4% 149.6 1.7 Still in place
South Carolina 137.1% 97.2% 42.5% 0.0% 20.9% 898.3 13.1% 651.4 8.1 May 4
Texas 153.7% 54.0% 73.5% 24.8% 55.9% 3,939.9 11.0% 3,110.4 29.4 April 30
Utah 42.0% 33.4% 49.9% 36.4% 6.4% 471.1 12.5% 244.6 2.1 May 1
West Virginia 72.9% 50.5% Decrease Decrease 24.1% 32.9 1.3% 22.9 0.1 May 4
Wyoming 202.0% 318.8% 58.8% N/A Decrease 21.6 4.3% 7.7 0.3 -*
NOTE: N/A: Insufficient data to report. Decrease signifies a percentage decrease in the metric over the past two weeks. Testing data only include tests with results. * Wyoming never issued a stay at home order.
SOURCE: KFF analysis of Johns Hopkins University COVID-19 Dashboard and The COVID Tracking Project data.

There are likely multiple policy, epidemiologic, and other factors driving these increases, including: when stay-at-home orders were lifted (and how long they were in place); the pace of reopening; the use of other social distancing measures (such as face mask requirements); increased population movement due to warming weather; outbreaks in congregate settings; the Memorial Day Holiday period; and, potentially, protests. For example, while 16 of the 20 states had lifted their stay-at-home orders by the end of May (California, Hawaii, and Oregon have maintained their stay-at-home orders as they have begun phased reopening), they did so at different paces (see Table 1). Many moved quickly, reopening businesses and lifting other restrictions within a two-week period. All states, except California, have lifted or eased bans on large gatherings and many have not required face masks, or have only recently done so after concerns were raised about rising cases. However, teasing out the role of these various factors and policy changes, many of which occurred simultaneously, will require further analysis.

What This All Means

Using these two metrics – increasing COVID-19 cases and positivity rates – over the most recent 14-day period, we find that almost 40% (20 states) are moving in the wrong direction. These hotspot states are primarily in the South and West, and most were not hit hard in the earliest days of the U.S. outbreak. Rising cases seen in these states now likely reflect an increase in transmission that began before the most recent two-week period and suggest that increasing hospitalizations could follow. In addition, their rising positivity rates indicate that the growth in cases is not due to increased testing and likely reflects an actual increase in transmission.

While these trends are concerning, and beginning to drive the national trend, most states (27) are moving in the right direction. Many of these states were among the last to reopen. Some phased in reopening over a longer time period and many have required the widespread use of face masks.

The factors determining which states are hotspots and which are not are difficult to tease out, but the inescapable reality is that the epidemic is getting worse, not better, in a significant portion of the country.

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