Arizona's third COVID wave has peaked and begun to recede.
Since our last update three weeks ago, the number of cases and new hospital admissions in the state has reached their peaks and begun to fall. Meanwhile, the state's data for deaths is still too incomplete over the last few weeks to confirm the pattern seen for cases and hospitalizations, but can be expected to follow.
In the following chart, we've aligned the rolling seven-day averages for the number of COVID cases, new hospital admissions, and deaths to the approximate date of exposure for the Arizonans affected by the spread of the various strains of the SARS-CoV-2 coronavirus. The chart is presented in linear scale, where you can see the third wave of infections begin to accelerate at the end of June 2021, which coincides with the mass exposure event of the Phoenix Suns advancing to the finals in the NBA playoffs. [Note the vertical scale of the chart is presented in logarithmic scale.]
The data indicates the incidence of initial exposure to the active variants of SARS-CoV-2 coronavirus in Arizona's third COVID wave peaked in the period between 11 August 2021 and 15 August 2021.
The data also confirms that COVID-19 has become less risky for Arizonans, with the number of new hospital admissions and deaths falling below the trendlines (shown as the dashed yellow lines for the third wave) that would be expected from the number of cases based on the patterns observed during the state's experience of its first two coronavirus waves in 2020. That change corresponds to the state's high rate of vaccination for its most vulnerable elderly population, where COVID tends to be less serious for those in younger demographic groups, whose rate of vaccination has been lower.
There is a point of concern in that the state's ICU Bed Usage for COVID patients is still in a rising trend. We've put togther the following animation to cycle through charts illustrating Arizona's data for COVID cases, new hospital admissions, deaths, and ICU Bed Usage, showing each frame for five seconds. The vertical scale on each of these charts is presented in linear scale.
The data confirms Arizona's third COVID wave peaked and began to recede at levels far lower than occurred during the state's first two waves.
Arizona is interesting because other than news reports communicating the rising number of hospitalizations and ICU bed usage at the time the incidence of cases and hospital admissions peaked, we have not been able to identify any state-level interventions that might explain the timing of its third peak.
Previously on Political Calculations
Here is our previous coverage of Arizona's experience with the coronavirus pandemic, presented in reverse chronological order.
- Arizona COVID Cases Rising in Third Wave
- Arizona COVID Cases on Slow Uptrend in Summer 2021
- Increase in Arizona COVID Cases from Border Migration Crisis Stabilizing
- COVID-19 and the 2021 Border Migration Crisis in Arizona
- Improving COVID Trends Bottom and Flatline in Arizona
- Surge of Migrants, Lifting of Business Capacity Limits Change Arizona COVID Trends
- COVID-19 in Retreat in Arizona With Vaccines Gaining Traction
- The Ebb and Flow of COVID-19 in Arizona's ICUs
- Arizona's Plunging COVID-19 Caseloads and the Vaccines
- Arizona Enters Downward Trend for COVID-19 After Second Peak
- Arizona Passes Second COVID-19 Peak
- A Tale of Two States and the Coronavirus
- COVID-19 Questions, Answers, and Lessons Learned from Arizona
- The Deadly Intersection of Anti-Police Protests and COVID-19
- 2020 Campaign Events Drive Surge in Arizona COVID Cases
- Arizona Arrives at Critical Junction for Coronavirus Cases
- Arizona To Soon Reach A Critical Junction For COVID-19
- 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?
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: Vaccine Administration. [Online Database]. Accessed 7 September 2021.
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]. 10 September 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.