Arizona's experience with the coronavirus pandemic is now reaching a critical junction. New coronavirus-related hospital admissions is steadily rising, reaching levels last seen when the state first became a national hotspot for coronavirus infections.

You can see that in our first chart showing the major trends for number of new COVID-19 hospital admissions in Arizona from 3 March 2020 through 9 November 2020. On the chart, we've indicated the major events that have corresponded with significant changes in the incidence of viral exposures that contributed to the changing trends.

Based on the back calculation method we're using to analyze Arizona's COVID data, the key inflection point in transitioning from a falling number of hospitalizations to a growing number appears to have taken place during the Labor Day holiday weekend. This period, indicated by the letter G on the chart, coincides with the reopening of high-exposure risk businesses (such as bars, gyms, theaters, etc.) in the state's most populous counties a week earlier, but which would have seen notably higher traffic and social mixing during the holiday weekend. Our thinking is that this combination of factors prompted to the reversal in the state's COVID hospitalization trajectory.

Those cases have continued to rise in September 2020 as Arizona progressively allowed previously shuttered high-exposure risk businesses to reopen on a county by county basis. By 23 September 2020, businesses in most Arizona counties had reopened (this is identified by the letter H on the chart), and on 1 October 2020, the relatively low population Graham County became the final Arizona county to meet the state's requirements to allow these previously closed business venues to reopen.

A Critical Junction

By itself, the number of new hospital admissions in Arizona is still well manageable, but the state will soon reach a critical junction for a limited resource: its available number of ICU beds. Our second chart confirms this assessment, as COVID-19 patient usage of ICU beds has entered the zone where hospital officials will need to begin actively managing this resource to ensure its availability to the patients who need it the most.

Unless the upward trend for ICU bed usage slows, or new ICU bed capacity is added within the state, we anticipate that state and county officials may act to restrict the operation of high-exposure risk businesses within the next several weeks.

Confirmed COVID-19 Cases and Deaths in Arizona

We've largely followed Arizona because the state's Department of Health Services provides high quality, detailed data following the progression of COVID-19 within the state. In fact, the COVID Tracking Project gives the state of Arizona an A+ for the quality of its coronavirus data, which contrasts greatly with other states, such as Illinois, whose public health officials have proven to be poorly equipped to communicate useful information with the public.

To that end, we'll next update our chart showing Arizona's daily number of positive testing residents by the date their test samples were collected.

Note the sharp rise in the number of confirmed cases corresponding with Event H, which is the reopening of most high-exposure risk businesses in the state.

Next, here's the latest update of our chart showing the number of deaths attributed to COVID-19 in Arizona.

Compared to earlier in the year when it saw a similar number of cases, the current level of deaths is far lower, though it has recently begun to rise. Once again, that change follows shortly after the period that would be expected following Event H.

We think this outcome is a consequence of doctors and health care practicioners getting better at treating for COVID-19, which is becoming less deadly as a result. Combined with practices to protect the state's most vulnerable residents from becoming infected, Arizona is so far outperforming its earlier go-round with the coronavirus pandemic.

Previously on Political Calculations

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

• Getting More Than Care from Arizona's COVID ICU Beds
• Arizona's Decentralized Approach to Beating COVID
• Going Back to School with COVID-19
• Arizona Turns Second Corner Toward Crushing Coronavirus
• Arizona's Coronavirus Crest in Rear View Mirror
• The Coronavirus Turns a Corner in Arizona
• A Delayed First Wave Crests in the U.S. and a Second COVID-19 Wave Arrives
• The Coronavirus in Arizona
• A Closer Look at COVID-19 Deaths in Arizona
• The New Epicenter of COVID-19 in the U.S.
• How Long Does a Serious COVID Infection Typically Last?
• How Deadly is the COVID-19 Coronavirus?
• Governor Cuomo and the Coronavirus Models
• How Do False Test Outcomes Affect Estimates of the True Incidence of Coronavirus Infections?
• How Fast Could China's Coronavirus Spread?

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.