04 February 2021

Arizona Enters Downward Trend for COVID-19 After Second Peak

As expected, Arizona has entered a downward trend for COVID-19 cases, hospitalizations, and ICU bed usage during the past two weeks. Only the state's data for COVID-19 deaths has yet to definitively follow suit, mainly because it takes the longest to finalize. Regardless, this measure has clearly peaked and we anticipate it will soon join the state's other major COVID-19 metrics on a confirmed downward trajectory.

What's more, the back calculation method points to a clear turning point for the state's post-political campaign event initiated surge in coronavirus infections. Here are the latest updates to the charts showing Arizona's data for newly confirmed cases by sample collection date, daily ICU bed usage, deaths by date of death certificate, and new hospital admissions, covering the eleven month period from 3 March 2020 through 2 February 2021.

Arizona COVID-19 Newly Confirmed Cases by Date of Sample Collection, 3 March 2020 - 2 February 2021
Arizona COVID-19 New Hospital Admissions by Date of Admission, 3 March 2020 - 2 February 2021
Arizona COVID-19 New Deaths by Date of Death Certificate, 3 March 2020 - 2 February 2021
Arizona COVID-19 ICU Bed Usage by Day, 3 March 2020 - 2 February 2021

The turning point for Arizona's second statewide surge in SARS-CoV-2 coronavirus infections came with the end of 2020's holiday season with the New Year's holiday weekend. Since then, a general reduction in social gatherings would account for the change in trajectory.

That's important to note because the distribution of the Trump administration's Operation Warp Speed vaccines started in the state during the final weeks of December 2020, but not in high enough numbers to affect the rate of incidence of new infections, hospital admissions, ICU bed usage, or deaths covered by the relatively finalized data shown in these charts. These vaccinations targeted Arizona's health care workers and elderly population, with vaccination eligibility having recently been expanded to cover more the state's population.

We anticipate vaccinations will progressively play a larger role in driving down Arizona's COVID metrics in the data that will be reported in the weeks ahead. We should soon see the relative effects of Arizona's COVID vaccination effort in the state's age demographic-based data.

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.