Here's what you need to know about Arizona's COVID-19 death rate

Arizona has one of the highest COVID-19 infection rates in the U.S. and while its death rate has been rising, it is lower than many other areas that have been hard-hit by the respiratory illness.

The COVID-19 death rate in Arizona as of Wednesday was 48 per 100,000 people, up from 38.5 deaths per 100,000 people on July 20, data from the U.S. Centers for Disease Control and Prevention's COVID Tracker shows.

Arizona's death rate puts it at 15th in the country, according to the CDC, which separates New York City from New York state in its rankings. New York City has the highest rate in the country, at 280 deaths per 100,000 people, the Wednesday data shows. Hawaii has the lowest rate — two deaths per 100,000 people.

Among the states with higher COVID-19 death rates than Arizona are Pennsylvania, Illinois, Delaware and Michigan — all states with lower reported rates of infection.

The Arizona COVID-19 death rate as of Wednesday was close to the U.S. average of 46 deaths per 100,000 people. Both numbers are rising.

In terms of raw numbers, Arizona's death count of 3,454 known deaths as of Wednesday ranked 14th in the country, Johns Hopkins University says. The state of New York as of Wednesday had recorded the highest number of deaths in the country — 32,658, the data showed.

Here are five things to know about deaths and COVID-19 in Arizona:

The COVID-19 death rate is a 'lagging indicator'

The process of someone getting infected with the SARS-CoV-2 virus that causes COVID-19 and then being hospitalized and dying is not instant. A peak in hospitalizations could cause a spike in deaths about one to four weeks later.

Arizona's surge of COVID-19 cases happened later than some other parts of the country, which could explain why its death rates are lower.

"People have to be sick enough to be hospitalized and then gravely ill. That's not going to correlate with the number of cases," said Dr. Amesh Adalja, senior scholar at the Johns Hopkins Center for Health Security and an infectious disease physician.

"If you see 10 cases today and you are looking to see the deaths they are not going to be coming tomorrow because it takes some time of course for the deaths to accrue. People have to get sick enough that they die from this. That's why we call it a lagging indicator."

The lag can be longer if the spike in positive cases is predominantly younger people getting infected, Adalja said. There's a time lag from when the younger person gets infected to when they infect a vulnerable person and that person gets sick enough to die, he said.

"They are not synchronous with cases," he said. "The same is true on the other end. When cases start to go down, the deaths may still be high because it will take some time to see the lower burden of illness reflected in the death rate."

Arizona's death rate is unlikely to get as high as the rate in hard-hit New York City

How does the situation in Arizona compare with New York City?

"(Arizona's death rate) has the potential to go up since it is a lagging indicator," said Dr. Michael White, chief medical officer for Valleywise Health, which operates two hospitals in the Phoenix area. "Do I think it will get as high as New York? I do not."

Advances in interventions for COVID-19 since the onset of the pandemic in the U.S. include steroids, prone ventilation, Remedsivir and convalescent plasma. New York was hit early, when health providers were still learning how best to treat the illness, White said.

"Where we have the advantage over New York or the East Coast early in the pandemic is we have been able to learn from their experience about early interventions," White said.

Similarly, Dr. Marjorie Bessel, chief clinical officer for Banner Health, said she's hopeful that the lessons learned from hospitals on the East Coast, in addition to ongoing new information about COVID-19, will have a positive impact on mortality rates in Arizona.

Most Arizona COVID-19 deaths are in people over 65 but younger people are dying, too.

The majority — 72% — of the 3,454 known COVID-19 deaths in Arizona as of Wednesday were in people age 65 and older, data from the Arizona Department of Health Services says.

But people in younger demographics are dying of COVID-19, too.

One in five or 21% of people known to have died of COVID-19-related causes in Arizona have been age 45 to 64, the state data shows.

Twelve people under the age of 20 have died, and 204 people ages 20 to 44 have died of COVID-19-related causes, the Arizona data says.

COVID-19 in Arizona:In one day, the surge leaves no walk of life unscathed

When hospital systems get overwhelmed, mortality rates go up.

"We absolutely know by looking at other parts of this country as well as other parts of the world, that mortality rates are also absolutely going to go up when the health care systems get overwhelmed and crushed by an overwhelming number of cases of COVID," Banner Health's Bessel said.

"In Arizona we were really, really busy in July ... But what would have happened if that peak continued? What would have happened if we had another 1,000 patients on top of the 3,000 patients that we were caring for near the peak? Our mortality rates will likely be affected if we do that again, or even if we exceed what we just experienced."

In other words, now is not the time to be complacent about safe practices such as wearing a mask and social distancing, she said.

The number of patients hospitalized for COVID-19 in Arizona, "is really still quite large" and out-of-state nurses and respiratory therapists are still being utilized to meet patient demand, Bessel said.

Banner Health's supply chain continues to be disrupted. The health system is doing what it calls PPE (personal protective equipment) "preservation activities" — reusing masks, for example.

"Our ability to secure massive amounts of PPE remains still limited because everybody in the world is after the same PPE that we are," Bessel said. "Our staff are working extra, they are tired. We still have lots of staff working overtime in addition to the external staff to meet demands. We also have many of our physicians working extra shifts per month."

Death rates are not the only measure of COVID-19's damage.

Death rates per 100,000 people measures deaths proportionally to population, so that's why areas with the highest death rates do not necessarily have the most deaths overall.

Another way of measuring deaths is the fatality rate, which is the percent of deaths per 100 confirmed cases. This rate is also called the observed case-fatality ratio.

The fatality rate can be affected by several factors, including differences in the number of people tested, Johns Hopkins University says. With more testing, for example, more people with milder cases are identified, which lowers the case-fatality ratio.

Right now the U.S. fatality rate for COVID-19 is 3% of confirmed cases and in Arizona it's 2%, the Kaiser Family Foundation's data shows. In reality, the fatality rates are likely much lower, Johns Hopkins University's Adalja said.

"I think it's hard to make any kind of strong statement about the actual case-fatality ratio," Adalja said. "We're still missing probably tenfold cases. When you do look at some of the models and the CDC estimates, likely the case-fatality or infection-fatality ratio is less than 1%."

Death rates per 100,000 people and fatality rates are not the only measure of COVID-19's damage on the health of Arizonans.

The disease is causing long-term problems in many patients, including muscle weakness, ongoing breathing problems and neurological problems.

The need for COVID-19 aftercare is so great that the Arizona Department of Health services recently contracted with a nursing home company to secure more beds for post-hospital COVID-19 care.

Reach health care reporter Stephanie Innes at Stephanie.Innes@gannett.com or at 602-444-8369. Follow her on Twitter @stephanieinnes

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