Category Archives: risk

A Tale of Two States and the Coronavirus

Although California and Arizona are geographically next to each other, both states have had very different experiences with the coronavirus.

That's because unique circumstances within both states have affected the progression of SARS-CoV-2 coronavirus infections within each during the pandemic.

That observation is driven home when we compare the reporting of newly confirmed COVID-19 cases in both states. Here, because California doesn't make the same kind of high quality data available to the public that Arizona's Department of Health Services does, we're turning to Johns Hopkins CSSE COVID-19 Data as our data source for both states. Using this data will allow for a more apples-to-apples comparison for applying the back calculation technique we've developed in analyzing Arizona's experience with the coronavirus pandemic.

That technique involves identifying turning points that changed the trajectory of newly reported cases following events that changed the rate of incidence of new infections. These turning points begin appearing in the rolling seven-day moving averages for newly reported cases some 9 to 11 days after the events that changed the viral infections rate of incidence, which corresponds with when 95% of all infections following an initial exposure event have developed. This process identifies a specific window of time in which contemporary news reports involving large gatherings may be reviewed to identify any "superspreader" events that prompted the change in the rate at which the coronavirus spreads.

That's the background - let's look at what happened in California during the last four months of 2020.

Newly Reported COVID-19 Cases in California, 1 September - 31 December 2020

In this chart, the vertical dashed lines indicate when the trajectory of newly reported cases definitively broke from the seven day moving average trend immediately preceding it, as indicated by the heavy blue line. The orange-shaded vertical bands indicate the period some 9-11 days earlier in which the events triggering the change in trend would have occurred. We've labeled five events in the chart with letters from A through E, the following section describes the corresponding events and their subsequent effect on California's reported incidence of COVID-19 cases.

Major Milestones for COVID-19 in California

Event A: L.A. Lakers win NBA Championship

After several weeks of following a flat-line trend averaging 3,200 new cases per day, the incidence of COVID-19 cases in California notched up to average roughly 4,400 new cases per day beginning on 22 October 2020, with the increase largely contained within Los Angeles County. This change occured 10 days following the L.A. Lakers NBA championship on 12 October 2020, which saw large crowds in L.A. celebrating the victory. Compared to what happened later however, the Lakers victory had a comparatively low impact.

Event B: L.A. Dodgers win World Series

The Dodgers victory over the Tampa Bay Rays in the 2020 World Series was the real spark that ignited California's late surge of new coronavirus cases. Here, we see the change in trend with the number of cases rising definitively above their post-Lakers championship high on 6 November 2020. Ticking the calendar backward by 9 days puts us at 28 October 2020, which is when the Dodgers became baseball's world champions. Much larger crowds in L.A. celebrated the event, pointing to baseball's much larger fan base in the region. Following the Dodgers victory, Los Angeles County led California for growth in the number of new cases, with the surrounding counties that make up L.A.'s greater metropolitan area following suit.

Event C: "Emergency Brake" Restrictions Go Into Effect

The next significant change in trajectory took hold beginning on 25 November 2020 (Thanksgiving Day), 9 days after California Governor Newsom imposed new restrictions on the operations of California businesses. The restrictions appear to have been somewhat successful in sharply slowing the rate of increase that began with Dodgers' world series win, but proved to be short lived.

Event D: A Clumsy Curfew and Governor Newsom's Loss of Credibility

On 2 December 2020, the number of new COVID-19 cases in California began increasing faster than they had before. Tracking significant events backwards, we find Governor Newsom's announced month-long curfew was the trigger for the increase, although it occurred 12 days earlier, on 23 November 2020.

That's because the curfew announcement sparked a popular backlash against Governor Newsom, with large political protests beginning the following day, which falls within the expected 9-11 day window. The protests came as public outrage spiked following the publication of photos of Governor Newsom disregarding his COVID-19 rules at a dinner held at the exclusive French Laundry restaurant less than two weeks earlier.

Governor Newsom was far from the only Calfornian official to shred their own credibility through outright hypocrisy during this time. On 4 December 2020, Governor Newsom announced a new stay-at-home order for California residents, while local governments announced they would ban outdoor dining, but instead of reducing the state's upward COVID-19 trajectory as might be expected in the period from 13 through 15 December 2020, the number of cases rose sharply as many small restaurant owners and their customers began protesting the officials' apparent determination to destroy their businesses. These actions were further undermined when California's top public health official confirmed the state and local governments' new restrictions lacked any support from scientific data indicating they would be effective in slowing the rate of COVID-19 infections.

Update 22 January 2021: Infectious disease experts have identified the ban on outdoor dining as a primary cause of California's winter surge of excess coronavirus cases, hospitalizations, and deaths.

Event E: California's ICUs Fill Up with COVID Cases and Christmas Travel

It's not until 22 December 2020 that we see any reversal in California's COVID trends, which corresponds to events that transpired from 11 through 13 December 2020. Here, we think the key event that altered California's COVID-19 case trajectory were reports of ICUs in the state nearing their capacity. We think these stories combined with the caution that Californians planning to travel to celebrate Christmas with their families began adopting in advance of the holiday, where increased social distancing contributed to reversing the surge provoked by Governor Newsom's hypocrisy.

Meanwhile, During the Same Time in Arizona...

Arizona's coronavirus experience is very different from California's. The following chart tracks four significant events in the state's coronavirus experience in the period from 1 September 2020 through 31 December 2020, which we've labeled as Events F through I.

Newly Reported COVID-19 Cases in California, 1 September - 31 December 2020

Note the very different vertical scale in the chart as compared to California's! The following section describes the four events identified on the chart:

Major Milestones for COVID-19 in Arizona

Event F: High risk businesses reopen

Following its early summer surge in cases, Arizona's number of new COVID-19 cases had bottomed out with roughly 550 new cases reported each day through September. The number of new cases however began rising slowing after 3 October 2020, which points to events that occurred from 22 through 24 September 2020 as leading to the increase. There was no large single event in this case, but this period marks when most businesses believed to have high exposure risk for spreading COVID-19 infections were allowed to reopen in the state, though with some restrictions on their operations.

Events G and H: 2020 Political Campaign Events

2020 was unusual in that Arizona was a swing state for the U.S. presidential election. Unlike in California, both Republicans and Democrats held significant events across the state on two weekends preceding the 3 November 2020 election. The changes in trend some 9-11 days after these two weekends suggests these were superspreader events that boosted the rate of growth of new COVID-19 infections within Arizona, regardless of political party affiliation.

Event I: Arizona's ICUs Fill Up with COVID Cases and Christmas Travel

That upward trend in new cases continued until 19 December 2020, after which the number of new cases has begun decreasing. As with California, this change in trend follows widespread news reports from 9-11 days earlier indicating that ICUs in Arizona were nearing capacity.

Although they are adjacent to each other, the events that have contributed to the fall and winter surge in coronavirus cases in Arizona and California are very different from one another. At the same time, the two states have adopted very different strategies for coping with the coronavirus pandemic. Generally, Arizonans have been more free to engage in commerce and other activities than Californians have, with little apparent downside. Californians however have faced an increasing level of heavy-handed restrictions on their activities through these four months, with little apparent benefit. There are many lessons to be taken from this tale of two states and the coronavirus.

Bonus Update: 8 January 2021: Since we mentioned Arizona has higher quality COVID-19 data available, we'll add charts showing its data for newly confirmed cases by sample collection date, daily ICU bed usage, deaths by death certificate date, and new hospital admissions, covering the period from 3 March 2020 through 5 January 2021. Although the lag from exposure to change in trend for each chart is different, the back calculation method for each confirms the identification of significant events we discussed for Arizona above.

Arizona COVID-19 Confirmed Cases by Sample Collection Date, 3 March 2020 - 5 January 2021
Arizona COVID-19 ICU Bed Usage, 3 March 2020 - 5 January 2021
Arizona COVID-19 Deaths by Death Certificate Date, 3 March 2020 - 5 January 2021
Arizona COVID-19 New Hospital Admissions, 3 March 2020 - 5 January 2021

Of these charts, only the chart showing Arizona's ICU Bed Usage is fully current. Data for the other three charts are incomplete, where the most recent three weeks shown will be subject to revision during the next few weeks, especially for the most recent dates indicated on the charts.

COVID-19 Questions, Answers, and Lessons Learned from Arizona

This is the last time we're going to look at Arizona's experience with COVID-19 in 2020, so we thought it was a good time to answer some questions that have been hanging out for a while. Let's get right to it!

What effect did the Thanksgiving holiday have on Arizona's COVID trends?

This is a question we've been waiting for the data to fill in for a couple of weeks, where it is now complete enough to tell the answer is: None.

If the high volume of social mixing anticipated during the Thanksgiving holiday was going to change the trajectory of COVID-19 cases, hospitalizations, and deaths for the worse, as was feared, we would see an upward shift in the trends for these statistics starting as early as 10 days after the event.

Instead, we see the Thanksgiving holiday affected when people were tested for COVID-19 infections, which creates some noise in Arizona's data for confirmed cases. But aside from that holiday-related anomaly, we've seen no meaningful change in the trend that began with the political campaign events taking place in the state during the period of 23-25 October 2020.

But don't take our word for it. We have four charts to back that assessment up (newly confirmed cases, new hospital admissions, ICU bed usage, and deaths), where only the chart for Arizona's COVID-19 deaths does not yet confirm that observation. And that's only because it takes so much longer for the coronavirus-related deaths associated with a given event to take place and be reported.

Arizona: Newly Confirmed COVID-19 Cases by Sample Collection Date, 30 March 2020 - 14 December 2020
Arizona: COVID-19 New Hospital Admissions, 30 March 2020 - 14 December 2020
Arizona: COVID-19 ICU Bed Usage, 30 March 2020 - 14 December 2020
Arizona: COVID-19 Deaths, 30 March 2020 - 14 December 2020

Has mask wearing made a difference?

The short answer is: Apparently yes. We have two periods where we can compare a non-mask-wearing period with a mask-wearing period. The non-mask-wearing ran from 25 May 2020 through 2 July 2020, which covers the period of time from 10 days after Arizona lifted its stay-at-home order on residents and allowed most businesses to reopen following its initial lockdown order until 13 days after when Governor Doug Ducey issued an executive order allowing counties and local governments to require masks and set other operating restrictions on businesses. During this period, the number of new COVID-19 infections in Arizona was rising by an average of 62 cases per day. Here's the chart for cases again.

Arizona: Newly Confirmed COVID-19 Cases by Sample Collection Date, 30 March 2020 - 14 December 2020

The second period ran from 3 October 2020 through 1 November 2020, which corresponds to the period 10 days after when most of the operating restrictions Governor Ducey had imposed on high-exposure risk businesses at the end of June 2020 were lifted in most counties in the state to 10 days after the October 2020's political events that increased the rate of incidence of new infections in Arizona.

During this second period, Governor Ducey's executive order allowing counties and local jurisdictions to require mask wearing and to set other operating restrictions on businesses has remained in effect. Consequently, in places where 94% of Arizonans live, the rate of mask-wearing compliance has remained high, but with businesses operating at levels similar to what they did following the state's initial lockdown period. During this period, the rate the number of new COVID-19 infections in Arizona was rising by an average of 31 cases per day, half that of the period prior to counties and local governments being able to require masks be worn (this is shown as the "Post-Event H Trendline" on each chart).

The reason the answer to this question is not simply "Yes" is because mask wearing is not the only restriction that local governments implemented. They've also set capacity limits, required protective shields to protect business employees from potentially infected customers, and have mandated other measures that also would have an impact in addition to requiring the public wear masks while at businesses. All of which muddies the water for clearly determining if mask wearing is the primary influence in reducing the rate of new infections.

The most honest answer we can give with the available data is that mask wearing along with these other restrictions do make a difference.

What caused Arizona's uncontrolled surges in coronavirus cases?

The simplest answer is: Political activism. We've previously covered the deadly impact of Arizona's anti-police protests, but the impact of political campaign events in the state before the 3 November 2020 elections cannot be understated since larger numbers of people were involved, which you can see in the charts as the difference between the trajectory of COVID-19 cases, hospital admissions, ICU bed usage, and deaths and the "Post-Event H Trendline" shown on each. This assessment applies across Arizona and across political parties, where counties that went for Biden have been hit hard with surging coronavirus infections, just as other counties have that went for Trump or that were split between both presidential candidates.

The data suggests the best advice we can give to anyone seeking to avoid becoming infected with the SARS-CoV-2 coronavirus is to avoid any personal contact with political activists.

Previously on Political Calculations

We've been covering Arizona's experience with the coronavirus pandemic since the state first became a national hotspot early in the summer of 2020. Here's our previous Arizona coronavirus coverage presented in reverse chronological order, with a sampling of some of our other COVID analysis!

References

We've continued following Arizona's experience during the coronavirus pandemic because the state's Department of Health Services makes detailed, high quality time series data available, which makes it easy to apply the back calculation method to identify the timing and events that caused changes in the state's COVID-19 trends. This section links that that resource and many of the others we've found useful throughout the coronavirus pandemic.

Arizona Department of Health Services. COVID-19 Data Dashboard. [Online Application/Database].

Maricopa County Coronavirus Disease (COVID-19). COVID-19 Data Archive. Maricopa County Daily Data Reports. [PDF Document Directory, Daily Dashboard].

Stephen A. Lauer, Kyra H. Grantz, Qifang Bi, Forrest K. Jones, Qulu Zheng, Hannah R. Meredith, Andrew S. Azman, Nicholas G. Reich, Justin Lessler. The Incubation Period of Coronavirus Disease 2019 (COVID-19) From Publicly Reported Confirmed Cases: Estimation and Application. Annals of Internal Medicine, 5 May 2020. https://doi.org/10.7326/M20-0504.

U.S. Centers for Disease Control and Prevention. COVID-19 Pandemic Planning Scenarios. [PDF Document]. Updated 10 September 2020.

COVID Tracking Project. Most Recent Data. [Online Database]. Accessed 15 December 2020.

More or Less: Behind the Stats. Ethnic minority deaths, climate change and lockdown. Interview with Kit Yates discussing back calculation. BBC Radio 4. [Podcast: 8:18 to 14:07]. 29 April 2020.

The Deadly Intersection of Anti-Police Protests and COVID-19

On 25 May 2020, video of the tragic death of George Floyd in police custody in Minneapolis, Minnesota exploded across social media, quickly leading to mass public protests in many cities across the United States. Coming as many states were lifting their initial lockdowns aimed at limiting the spread of COVID-19, many public health officials worried the protests would cause a resurgence of new coronavirus infections.

In the months since, little evidence has emerged to indicate that the anti-police protests contributed to a surge of new SARS-CoV-2 coronavirus infections. A NBER working paper considered data collected in 315 U.S. cities and counties that experienced protests in the five weeks following George Floyd's death, demonstrating "the protests had little effect on the spread of COVID-19 for the entire population of the counties with protests" for all but one:

However, with the exception for Maricopa County, Arizona, we find essentially no evidence that protests contributed to significant or substantial increases in COVID-19 during the period following protest onset, consistent with our main difference-in-differences findings....

We've been following Arizona's experience during the coronavirus pandemic since we identified the state had become a national hotspot for infections in the early summer of 2020. We've continued following Arizona's experience because the state's Department of Health Services makes high quality, detailed time series data available. This data makes it possible to use back calculation techniques to identify the timing of events that changed the rate of incidence for coronavirus exposures, which in turn, changed the trend for COVID-19 infections within the state.

With that being the case, we are uniquely situated to quantify the impact of 2020's anti-police protests on the spread of COVID-19 in the one state where these two factors intersected with deadly effect. In the following sections, we'll estimate the number of excess COVID-19 cases that resulted from the mass protests that took place within Arizona, along with the number of excess hospital admissions and the number of excess deaths that were attributed to COVID-19 following the protests.

Excess COVID-19 Cases Resulting from Anti-Police Protests

Arizona tracks its confirmed COVID-19 cases by their sample collection dates. Since the onset of COVID-19 symptoms is a significant driver of testing activity, occurring a median of five days after initial exposure with 95% of tests occurring within ten days following this initial viral exposure, we can use the date for positive test results to predict when a turning point will be seen following an event that significantly changed the incidence of viral exposures within a population. These figures apply when sufficient test kits and testing capacity are available to process COVID-19 tests without delays.

In Arizona, 28 May 2020 marked the first day of mass anti-police protests, which were concentrated in Maricopa County and specifically within the city of Phoenix. Adding 10 days to this date suggests that any turning point related to anti-police protests would start after 7 June 2020.

That's exactly what we observe in the following chart, showing the number of confirmed COVID-19 cases in Arizona by their sample collection date.

Confirmed COVID-19 Cases in Arizona by Sample Collection Date, 3 March 2020 - 4 December 2020 (based on data available through 7 December 2020)

The protests had high participation through 7 June 2020, before the crowds dwindled and finally petered out on 15 June 2020.

That noted, we can use the counterfactual of the trend that existed prior to the protests to estimate the number of excess COVID-19 cases that were recorded after 7 June 2020. We estimate Arizona experienced at least 29,061 more COVID-19 cases as a consequence of the anti-police protests, which is indicated by the shaded red area on the chart.

Excess Hospital Admissions Due to Anti-Police Protests

Arizona's Department of Health Services provides its data for the daily number of new COVID-19 hospital admissions. Here, we note that COVID-19 hospitalizations typically follow some 11 to 13 days following the initial viral exposure, where we would expect to see a surge of new admissions with respect to a counterfactual based on the pre-existing trend on or shortly after 8 June 2020.

Once again, that's what we observe in the data. The next chart shows the number of daily COVID-19 new hospital admissions in Arizona during the nine months from 3 March 2020 through 4 December 2020.

Daily COVID-19 New Hospital Admissions in Arizona, 3 March 2020 - 4 December 2020 (based on data available through 7 December 2020)

Here, we estimate Arizona experienced at least 2,608 more COVID-19 hospitalizations than it would otherwise have because of the anti-police protests, which is indicated by the shaded red area on the chart.

Excess Deaths Due to Anti-Police Protests

Arizona reports data for the number of actual deaths attributed to COVID-19 per day. Typically, deaths from COVID-19 follow some 17 to 21 days after the date of initial exposure to the SARS-CoV-2 coronavirus. With 28 May 2020 as the starting point, this lag would put the expecting timing of an increase in coronavirus-related deaths in Arizona resulting from the social mixing that occurred as part of the anti-police protests on or shortly after 14 June 2020.

Or would, if not for the demographics associated with the anti-police protests. By and large, individuals below the age of 45 were the main participants in the protests, where fewer than six percent of all deaths attributed to COVID-19 in Arizona have occurred within this age group.

However, that doesn't mean the anti-police protests didn't result in a surge of COVID-19 deaths in the state. We think that after large scale protests in Arizona ended on 7 June 2020, participants carrying coronavirus infections went home, so to speak, where their subsequent social interactions would result in the infection of older Arizonans. Using 7 June 2020 as the starting point for those post-protest interactions, that would put the expected timing of a change in trend for COVID-19 deaths between 25 June 2020 and 28 June 2020.

This scenario fits what we observe in the following chart showing the number of deaths attributed to COVID-19 each day in Arizona from 3 March 2020 through 4 December 2020.

Daily COVID-19 Deaths in Arizona, 3 March 2020 - 4 December 2020 (based on data available through 7 December 2020)

We estimate Arizona experienced at least 594 more coronavirus-related deaths than it would otherwise have due to the anti-police protests, which is indicated by the shaded red area on the chart.

Personal Injuries and Wrongful Deaths

What if the organizers of Arizona's anti-police protests were held accountable for the excess COVID-19 hospitalizations and deaths that occurred as a consequence of their actions?

That's a real question because there were activists in Arizona who recognized the risk of spreading COVID-19 infections, who chose to not engage in mass protests. BLM activist Lola Rainey explains her thinking for why she didn't organize mass street protests in Tucson, Arizona:

"When you talk about taking to the streets an organized movement like that, you have to be aware that you're putting other people's lives at risk. One, because we are in a pandemic, and there are a lot of things you cannot control when people are out in the streets like that,” said Rainey.

Alas, that kind of responsible thinking wasn't anywhere to be found in Phoenix, Arizona, where disputes among protest organizers all but ensured an uncontrolled situation that would promote the spread of coronavirus infections, with participants engaging in behaviors that ran counter to the guidance of public health officials.

In that regard, the various organizers and promoters of the anti-police protests could be held legally liable for the excess COVID-19 hospitalizations and deaths that resulted from their collective actions and negligence, if any enterprising trial attorneys were looking to score some easy personal injury and wrongful death settlements.

Using data from California, the median personal injury settlement is $114,305, so Arizona's protest-related 2,608 excess COVID-19 hospitalizations could represent a $332 million payday for the injured and their lawyers. Meanwhile, with a median wrongful death award of $2.2 million, the corresponding payout for wrongful death claims could total over $1.3 billion. With numbers like that, how long do you suppose it might be before class action lawsuits start being filed by hungry attorneys representing damaged clients?

Why Is the Deadly Intersection of Anti-Police Protests and COVID-19 in Arizona?

The previous section explains "why Phoenix?", but a larger question is "why Arizona?"

We suspect the answer lies in a unique confluence of events. For one, Arizona is unique in its climate. Unlike nearly all other places where mass anti-police protests occurred at this time, the city of Phoenix was already registering daily high temperatures between 100 and 110 degrees Fahrenheit at the end of May 2020 and in early June 2020. Those kinds of temperatures mean that groups of protesters would periodically break away from protesting to cool off in air-conditioned environments. Such environments have been found to be conducive for spreading respiratory viruses like SARS-CoV-2, providing an additional factor for increasing the incidence of infections beyond that from direct participation in the protests.

We think the timing of Arizona's initial lockdown period also played a significant role. Arizona lifted its statewide lockdown on 15 May 2020, which led to a steady but managable growth in the number of infections in the following weeks. At the time of the protests, that increase had provided a critical mass of infected individuals that would fuel a surge of new infections under the conditions of a large, uncontrolled event like mass political protests where social distancing would not be effectively practiced.

Though Arizona's leaders could not have possibly forecast such an event would occur when it did, we can compare the state's experience with that of Nevada, where Las Vegas is the only other major city in the U.S. with a climate similar to Phoenix to test this factor. Here, we find that Nevada delayed lifting its lockdown for nearly two weeks after Arizona, which meant it had a much smaller pool of infected individuals at the start of its protests. Those lower numbers would have greatly reduced its risk of experiencing a surge in cases at the time of the protests, which potentially explains "why Arizona and why not Nevada?", even though both share similar hot, arid climates.

If it wasn't already clear, the role of protest organizers and those supporting or promoting them in contributing to the conditions that promoted the spread of COVID-19 in Arizona cannot be overstated.

There may be additional, lesser factors to consider, but these are the big three that could very well explain most of why the intersection of anti-police protests and COVID-19 proved to be so deadly in Arizona and not elsewhere in the United States.

A Resurgence of Cases

Finally, we should recognize the surge in coronavirus cases that Arizona is currently experiencing. We've previously traced the origin of the current surge to 2020 political campaign events occurring two and a half weeks before the 3 November 2020 election, which stand out because they involved many more people than the anti-police protests did. On 3 December 2020, Arizona Governor Doug Ducey initiated new restrictions on large events and businesses in the state. We should first start seeing any effects from the new restrictions in the state's data for cases and hospital admissions reported after 14 December 2020.

Celebrating Political Calculations' Anniversary

Our anniversary posts typically represent the biggest ideas and celebration of the original work we develop here each year. Here are our landmark posts from previous years:

  • A Year's Worth of Tools (2005) - we celebrated our first anniversary by listing all the tools we created in our first year. There were just 48 back then. Today, there are over 300....
  • The S&P 500 At Your Fingertips (2006) - the most popular tool we've ever created, allowing users to calculate the rate of return for investments in the S&P 500, both with and without the effects of inflation, and with and without the reinvestment of dividends, between any two months since January 1871.
  • The Sun, In the Center (2007) - we identify the primary driver of stock prices and describe a whole new way to visualize where they're going (especially in periods of order!)
  • Acceleration, Amplification and Shifting Time (2008) - we apply elements of chaos theory to describe and predict how stock prices will change, even in periods of disorder.
  • The Trigger Point for Taxes (2009) - we work out both when, and by how much, U.S. politicians are likely to change the top U.S. income tax rate. Sadly, events in recent years have proven us right.
  • The Zero Deficit Line (2010) - a whole new way to find out how much federal government spending Americans can really afford and how much Americans cannot really afford!
  • Can Increasing the Minimum Wage Boost GDP? (2011) - using data for teens and young adults spanning 1994 and 2010, not only do we demonstrate that increasing the minimum wage fails to increase GDP, we demonstrate that it reduces employment and increases income inequality as well!
  • The Discovery of the Unseen (2012) - we go where so-called experts on income inequality fear to tread and reveal that U.S. household income inequality has increased over time mostly because more Americans live alone!

We marked our 2013 anniversary in three parts, since we were telling a story too big to be told in a single blog post! Here they are:

  • The Major Trends in U.S. Income Inequality Since 1947 (2013, Part 1) - we revisit the U.S. Census Bureau's income inequality data for American individuals, families and households to see what it really tells us.
  • The Widows Peak (2013, Part 2) - we identify when the dramatic increase in the number of Americans living alone really occurred and identify which Americans found themselves in that situation.
  • The Men Who Weren't There (2013, Part 3) - our final anniversary post installment explores the lasting impact of the men who died in the service of their country in World War 2 and the hole in society that they left behind, which was felt decades later as the dramatic increase in income inequality for U.S. families and households.

Resuming our list of anniversary posts....

Previously on Political Calculations

Here's our previous Arizona coronavirus coverage presented in reverse chronological order, with a sampling of some of our other COVID analysis!

References

Arizona Department of Health Services. COVID-19 Data Dashboard. [Online Application/Database].

Maricopa County Coronavirus Disease (COVID-19). COVID-19 Data Archive. Maricopa County Daily Data Reports. [PDF Document Directory, Daily Dashboard].

Stephen A. Lauer, Kyra H. Grantz, Qifang Bi, Forrest K. Jones, Qulu Zheng, Hannah R. Meredith, Andrew S. Azman, Nicholas G. Reich, Justin Lessler. The Incubation Period of Coronavirus Disease 2019 (COVID-19) From Publicly Reported Confirmed Cases: Estimation and Application. Annals of Internal Medicine, 5 May 2020. https://doi.org/10.7326/M20-0504.

U.S. Centers for Disease Control and Prevention. COVID-19 Pandemic Planning Scenarios. [PDF Document]. Updated 10 September 2020.

COVID Tracking Project. Most Recent Data. [Online Database]. Accessed 10 November 2020.

More or Less: Behind the Stats. Ethnic minority deaths, climate change and lockdown. Interview with Kit Yates discussing back calculation. BBC Radio 4. [Podcast: 8:18 to 14:07]. 29 April 2020.

Arizona Arrives at Critical Junction for Coronavirus Cases

One week ago, we projected the state of Arizona would soon arrive at a critical juncture in its experience with the coronavirus pandemic. With the rate of ICU bed usage in the state for COVID-19 patients now surpassing a key threshold, that time has now arrived.

That state of affairs may be seen in a chart tracking Daily COVID-19 ICU Bed Usage in Arizona, where the number of beds occupied by COVID-19 patients now exceeds the level would be considered easily sustainable.

Daily COVID-19 ICU Bed Usage in Arizona, 3 March 2020 - 18 November 2020

Arizona's hospitals still have available ICU bed capacity, so the situation in the state isn't as critical as other areas that are currently experiencing a significant surge in cases. What exceeding this threshold means is that Arizona hospitals need to begin more actively managing their ICU beds usage to accommodate the rising numbers of COVID-19 patients. Ideally, those measures will involve increasing their ICU bed capacity. Unlike many states, Arizona saw two new hospitals open this month in its major metropolitan areas, which will provide some additional breathing room.

Sharp eyed readers will note we've added a new event to this chart. Event I marks an increase in the trend for COVID-19 ICU bed usage that coincides with political events that took place in the state during the period from 23 October 2020 through 25 October 2020. Using the back calculation method to identify the period in which the incidence of coronavirus exposures points to this period as a significant event. The latest update to our chart tracking daily new COVID-19 hospital admissions in Arizona identifies each of the major events associated with a changes in the risk of coronavirus exposure among Arizona's population.

Daily COVID-19 New Hospital Admissions in Arizona, 3 March 2020 - 18 November 2020

The data for this latter chart is still incomplete, where the ICU bed usage chart has proven to be a good real time indicator of the progression of SARS-CoV-2 coronavirus infections within the state. We anticipate the rolling 7-day moving average will soon confirm the surge in COVID-19 hospitalizations.

Data for positive COVID-19 test results in Arizona already confirms a surge in new cases, pointing once again to the period of 23 October 2020 through 25 October 2020 as the period in which the incidence of new infections increased. The following chart of daily newly confirmed COVID-19 cases in Arizona shows the latest surge:

Daily COVID-19 Confirmed Cases by Sample Collection Date in Arizona, 3 March 2020 - 18 November 2020

Meanwhile, since it has the greatest lag between the incidence of exposure and observed change in trend, a chart of deaths attributed to COVID-19 in Arizona does not yet confirm a change in trend. We project the rolling 7-day moving average of coronavirus deaths will show a change in trend taking place in the period from 9 November through 13 November 2020 as these deaths are reported in the weeks ahead.

Daily COVID-19 Deaths in Arizona, 3 March 2020 - 18 November 2020

We track Arizona's COVID-19 data because the state provides high quality, relatively detailed data that makes it possible to use the back calculation method to identify when the rate of incidence of coronavirus infections has changed for the state's residents. To better show how that method works, we put together the following chart to track the incidence of COVID-19 infections among the various demographic age groups reported by Arizona's Department of Health Services. The chart focuses on the time from 9 August 2020 through 18 November 2020, which covers Arizona's 'back-to-school' period for its state universities.

In this chart, we're identifying trend-changing events by number instead of letter, so here's the basic summary:

  1. 20-22 August 2020: In-person classes begin at state universities.
  2. 4-6 September 2020: Social mixing during Labor Day weekend.
  3. 13-15 September 2020: University of Arizona imposes lockdown measures on its students (the outbreak of cases in the state during this time was concentrated at the UA campus). After this third significant event affecting the incidence of new coronavirus cases in Arizona, it's important to note the divergence that takes place among demographic age groups in the state. The Age 0-19 group sees a falling number of cases, as Arizona schools have measures that are largely effective in limiting the spread of new cases. But the Age 20-44 group sees an increasing number of cases as compared to all other age groups, where this group is the most likely to frequent high exposure risk venues, such as bars, gyms, and other businesses for which public health officials have established specific operating requirements.
  4. 23-25 October 2020: Political rallies centered around the occasion of the 24 October 2020 National Vote Early Day, less than two weeks ahead of the U.S. elections.

The current upward trend in cases and what we can identify as contributing factors to it using the back calculation method suggests the most effective approach state and local government officials can take to reverse its adverse trend would be to restrict the operation of high exposure risk businesses in local communities as the ICU beds usage within them nears 95% of capacity. Arizona has already demonstrated a decentralized approach can be highly effective in coping with a surge in cases, without unnecessarily imposing economic hardships on the state's residents in areas where the number of cases and burden on loal hospital resources is relatively low.

Local officials could also mandate wearing masks at public venues within their jurisdictions, though we think this option would provide little benefit. That is because most areas in the state already have relatively high rates of compliance with wearing masks inside local businesses, where there is little evidence to suggest a statewide mandate would significantly alter the trend. The current situation differs from the situation that applied during the summer when Arizona became a national hotspot for COVID-19 infections, when the rate of mask wearing was very low prior to the state governor's order allowing local officials to impose mask wearing requirements for their residents. Starting from an already higher level of mask wearing, any additional benefit that might be realized is much smaller.

With the elections now in the past, removing that contributor to the risk of virus exposure, Arizona's next challenge in its coronavirus pandemic experience will be to address the social mixing that will take place during the Thanksgiving holiday. We'll present our next follow up after the holidays to see how the state fared.

Previously on Political Calculations

Here's our previous Arizona coronavirus coverage, with a sampling of some of our other COVID analysis!

References

Arizona Department of Health Services. COVID-19 Data Dashboard. [Online Application/Database].

Maricopa County Coronavirus Disease (COVID-19). COVID-19 Data Archive. Maricopa County Daily Data Reports. [PDF Document Directory, Daily Dashboard].

Stephen A. Lauer, Kyra H. Grantz, Qifang Bi, Forrest K. Jones, Qulu Zheng, Hannah R. Meredith, Andrew S. Azman, Nicholas G. Reich, Justin Lessler. The Incubation Period of Coronavirus Disease 2019 (COVID-19) From Publicly Reported Confirmed Cases: Estimation and Application. Annals of Internal Medicine, 5 May 2020. https://doi.org/10.7326/M20-0504.

U.S. Centers for Disease Control and Prevention. COVID-19 Pandemic Planning Scenarios. [PDF Document]. Updated 10 September 2020.

COVID Tracking Project. Most Recent Data. [Online Database]. Accessed 10 November 2020.

More or Less: Behind the Stats. Ethnic minority deaths, climate change and lockdown. Interview with Kit Yates discussing back calculation. BBC Radio 4. [Podcast: 8:18 to 14:07]. 29 April 2020.