AZ reports a high 1,753 new COVID-19 cases as health department includes antigen diagnostic tests

Arizona reported 1,753 new COVID-19 cases and 38 new known deaths on Thursday, with a high number of new cases in part because of the new inclusion of all positive results from antigen diagnostic tests. 

Hospitalization metrics such as patient counts and ventilators in use for COVID-19 have generally been trending downward for about nine weeks, with several metrics back to levels from early April, according to hospital data reported to the state. 

Identified cases rose to 211,660 and known deaths totaled 5,409, according to the daily report by the Arizona Department of Health Services. The 38 new known deaths reported on Thursday represent the new deaths identified by the state Health Department that day, but many occurred days and weeks prior. 

The 1,753 new cases is the highest daily report since Aug. 1. The Heath Department posted on Thursday that the data includes a large number of PCR diagnostic tests submitted from Arizona State University. 

ASU said the results came from a variety of people, not just the ASU community. Tests also include those for the general public and members of outside groups the university provides testing for. 

"As directed, ASU has been submitting all of its data to AZDHS on a daily basis and on a regular schedule. Our understanding is that today’s ADHS reporting reflects test results that the department did not previously report, dating back to cases in July and August, the majority of which represent ASU’s public and partner testing sites," according to a statement from ASU.

"Based on demographics of the cases reported as positive, it reflects a geography and age distribution representative of the entire county, not ASU students or employees." 

The department also is now including as probable cases anyone with a positive antigen test, another type of test to determine current infection. According to ADHS, 577 probable cases from antigen tests were added to the numbers Thursday, mostly collected in September in Pima County. The remaining positive antigen tests from the past several months will be added to the data dashboard Friday. As of Thursday, probable cases made up 1% of the state's 211,660 identified cases, according to the department.

Antigen tests (not related to antibody tests) are a newer type of COVID-19 diagnostic test that use a nasal swab or other fluid sample to test for current infection. Results are typically produced within 15 minutes.

Before Thursday, case reports have fluctuated between about 80 and 1,100 daily over the past three weeks.

Thursday's dashboard shows 83% of inpatient beds and 79% of ICU beds in use, which includes people being treated for COVID-19 and other patients. COVID-19 patients were using 7% of all inpatient beds and 7% of ICU beds. Overall, 25% of ventilators were in use.

The number of weekly tests conducted dropped significantly in July and into August, after which it's remained flatter with slight decreases.

Of known test results from the past four weeks, 4-5% have come back positive, according to the state, which has a unique way of calculating percent positivity. 

Johns Hopkins University calculates Arizona's seven-day moving average of percent positives at 5.7% and shows it has generally trended downward in recent weeks but is now at more of a plateau. 

A positivity rate of 5% is considered a good benchmark that the spread of the disease is under control. 

Here's what you need to know about Thursday's new numbers.

Reported cases in Arizona: 211,660

• Cases increased by 1,753, or 0.84%, from Wednesday's 209,907 identified cases since the outbreak began. ADHS said the large number of new cases is due to the largest daily number of lab results reported so far as well as an expanded case definition to include antigen tests as well as PCR tests.  
• County cases: 139,051 in Maricopa, 23,563 in Pima, 12,472 in Yuma, 10,263 in Pinal, 5,733 in Navajo, 3,817 in Mohave, 3,644 in Coconino, 3,417 in Apache, 2,801 in Santa Cruz, 2,442 in Yavapai, 1,872 in Cochise, 1,208 in Gila, 786 in Graham, 530 in La Paz and 58 in Greenlee, according to state numbers.
• The rate of cases per 100,000 people is highest in Yuma County, followed by Santa Cruz County, Navajo and Apache counties. 
• The Navajo Nation reported 10,059 cases and 539 confirmed deaths as of Wednesday. The Navajo Nation includes parts of Arizona, New Mexico and Utah.
• The Arizona Department of Corrections said 2,517 inmates had tested positive for COVID-19 as of Wednesday, including 967 in Tucson; 39,493 inmates have been tested; 47 test results are pending. Thirteen incarcerated people have been confirmed to have died of COVID-19, with 14 additional deaths under investigation.  
• While race/ethnicity is unknown for 32% of cases, 31% of cases are Hispanic or Latino, 24% of cases are white, 6% are Native American, 3% are Black and 1% are Asian/Pacific Islander.
• Laboratories have completed 1,350,116 diagnostic tests for COVID-19, 11.7% of which have come back positive. That number now includes both PCR and antigen testing. The percentage of positive tests had increased since mid-May but began decreasing in July. It was around 4-5% for tests that have come back so far from the past four weeks, according to state numbers, which leave out data from labs that do not report electronically.

Reported deaths: 5,409 known deaths 

• On Thursday, 38 new deaths were reported, although many occurred days and weeks prior. 
• County deaths: 3,210 in Maricopa, 612 in Pima, 341 in Yuma, 231 in Navajo, 221 in Mohave, 200 in Pinal, 159 in Apache, 133 in Coconino, 80 in Yavapai, 69 in Cochise, 61 in Santa Cruz, 51 in Gila, 24 in Graham, 15 in La Paz and fewer than three in Greenlee.
• People aged 65 and older made up 3,852 of the 5,409 deaths, or 71%.
• While race/ethnicity is unknown for 11% of deaths, 42% of those who died were white, 31% were Hispanic or Latino, 11% were Native American, 3% were Black and 1% were Asian/Pacific Islander.

Slight inpatient uptick as other hospital metrics continue steady decline

• Inpatients with suspected and confirmed COVID-19 were counted at 594 on Wednesday, an uptick from the past week's levels. Inpatient numbers have generally been trending downward for more than nine weeks. Hospitalizations surpassed 3,000 daily for much of July.
• ICU bed use for suspected and confirmed COVID-19 patients was at 119 beds in use on Wednesday. ICU bed occupancy for COVID-19 patients is at its lowest level reported since early April. Occupied beds have seen gradual decreases for about nine weeks.
• Ventilator use for suspected and confirmed COVID-19 patients was at 65 on Wednesday, the lowest it has been since hospitals began reporting the data in early April. Ventilator numbers have generally been declining for about nine weeks, after hitting a record high 687 ventilators in use on July 16.
• Emergency department visits for patients with suspected and confirmed COVID-19 was at 863 on Wednesday. With a few exceptions, daily ER visits are gradually trending downward. Daily ER visits first surpassed 1,000 on June 16 and were above that level nearly every day since, until daily ER visits dropped below 1,000 on Aug. 9. The number since then has hovered around or below 1,000.
• The number of patients with suspected and confirmed positive COVID-19 discharged from hospitals was at 131 patients discharged on Wednesday. July saw relatively high discharge numbers, which generally have been decreasing since then.

Reach the reporter at Alison.Steinbach@arizonarepublic.com or at 602-444-4282. Follow her on Twitter @alisteinbach.

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