COVID by the numbers: Increases may be slowing; higher Monday numbers

Posted at 5:07 PM, Dec 21, 2020

The Arizona Department of Health Services reported 7,748 COVID-19 cases in Arizona Monday, this is the fifth highest report on record.

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Shifting Reporting patterns of Cases

Monday’s are typically a low reporting day due to the normal weekend lag, but an Arizona Department of Health Services spokesperson told ABC15 that they are working to change this to balance out how cases are reported in Arizona so that Tuesday’s number is not so high. Tuesday is often one of Arizona’s highest COVID-19 reporting days, coming at number one eight times since March 29, when Arizona began adding more than a thousand cases a week to the total.

Friday, another high reporting day for Arizona, also has come in as the highest reporting day of the week eight times since March 29, but has added more COVID-19 cases to the overall total. 77,540 cases have been reported on Friday, the most of any day of the week, this is followed by Tuesday at 75,214 and Saturday at 73,885.


Day of the WeekCases AddedRank

Slowing Case Growth in Arizona

Even with the higher numbers added Monday, there are indications that Arizona’s case growth is beginning to slow down.

According to, a website that tracks COVID-19’s reproduction number over time (Rt), Arizona is now at 1.04. Last week Arizona was typically calculated at 1.14 or higher on any given day. To give an idea of what this number means, right now it is estimated that if 100 Arizonans had COVID-19 they would infect 104 people, suggesting the virus continues to grow in the state, but at only marginal levels.

On top of this, cases added to Arizona’s epi curve, the date when a case came back positive, is only up 1.7% from the week prior using data that was collected from the past four days. This same number was closer to 15% for cases added the week of 12/14.

Still, documenting Arizona’s true weekly COVID-19 case changes in real-time is problematic, since we do not know what tomorrow’s case report will bring, and reported numbers can drastically change the numbers for any of the past 5 days.