Despite widespread calls in Arizona and nationally for more coronavirus testing in order to safely reopen the economy, COVID-19 testing in Arizona has trended downward for weeks, according to the state's official tally.

The high-water mark for tests came four weeks ago, during the week that ended March 28, when 12,728 tests were conducted. Since then, weekly testing numbers fell to 11,864, and then 10,684 for the week ending April 11.

The number edged up last week, to 11,127 tests, according to state data on Thursday. But that figure is still 13% lowerthan the number of tests done at the end of March, just before Gov. Doug Ducey issued his "Stay Home, Stay Healthy, Stay Connected" order shuttingdown the state.

Meanwhile, as the number of tests has declined, the percentage of positive tests has increased, which four public health experts say indicates the state is not testing enough for COVID-19. Positive tests should drop as a share of total tests as testing becomes more widespread, the experts said.

Plentiful testing is seen as the main requirement to safely reopen the state's economy and prevent future outbreaks that couldslow a recovery. One expert estimated Arizona needs 100,000 tests a month to safely reopen.

Over the past four weeks, the percentage of tests coming back positive rose from 7% for the week that ended March 28, to 9% the next week and then 11% for the weeks ending April 11 and April 18. This week, the share of positive tests rose to 12%.

"If you are doing tests for sort of everyone, not just particularly symptomatic people, the positive rate should go down," said Dr. Murtaza Akhter, an assistant professor in the Department of Emergency Medicine at the University of Arizona College of Medicine-Phoenix.

Akhter, who works in emergency rooms for Valleywide Health, Florence Hospital and hospitals in Pennsylvania and Masschusetts, said hospitals' strict testing policies might be contributing to the downward trend in testing. Many people who seek care in hospital emergency departments are only being tested if they are "deemed to be sick enough to be tested" based on hospital policy.

"If you are going to come in and be discharged, then you may not get tested at all," he said. "You only get tested if you aresick enough to be admitted."

One hospital outside Arizona where he works has a rapid-turnaround test for those who are admitted and another, slower test for people who aren't.

He said people who are sick enough to be admitted to the hospital are more likely to have COVID-19, which is why the percentage of positive tests may be higher. The number of tests in Arizona could also be dropping because physical distancing measures are working and the number of infections is dropping, Akhter said.

Dr. Cara Christ, director of the Arizona Department of Health Services, said Thursday that the state's guidance on testing has changed and anyone who has been exposed to COVID-19 should now be able to get a test. Previously, the state discouraged widespread testing because of a lack of tests, although Ducey has consistently said he wants more testing to be done.

Ducey, at a news conference this week, said supply chain issues are being resolved and there are plans to ramp up testing.

David Dausey, provost and professor of health science at Duquesne University, said Arizona is not alone in seeing testing declines.

"Testing in this country is a colossal mess," Dausey said."And it all has to do with supply chains and the fact that these tests, and putting them together, are actually complex enough that they require ... materials from a variety of different places. And what we're running into are shortages and getting access to those materials to create the tests."

The country relies on "just-in-time delivery" for much of the economy. While that's an efficient and businesslike approach, it can fail during a surge in demand for different components from around the world.

Dausey said a lack of leadership from the federal government has exacerbated problems.

"People have described it as survival of the fittest," he said. "You've got states competing against states to get the tests. And companies competing against companies to get the components to make the tests."

Positive tests increasing

The 12% of positive tests in Arizona, as of Thursday, compares favorably with other states and numbers nationally, said Jennifer Horney, professor and founding director of the program in epidemiology at the University of Delaware.

Nationally, the positive rate is about 18% overall and 21% more recently, Horney said. Massachusetts is at 25% to 30% positive, while Georgia is at 23%, indicating those states have much more testing to do, she said.

But Arizona's rising rate of positive tests means more testing is needed to identify sick people who continue to spread the virus, she said. Arizona's testing rates also are not uniform between counties, which indicates a need for more tests.

"If a higher percentage of tests come back positive, then it's clear there's not enough testing to capture all the infected people," Horney said. "So basically you're testing people that you're pretty sure already areinfected and not really identifying any new cases."

The World Health Organization issued new guidance that if the number of positive tests is at 10%, then enough tests are being done in the area. That indicates because Arizona's positive percentage has now increased to 12%, more tests are needed here, Horney said.

Dausey said the fact that hospitals will only give tests to patients who are admitted also shows the need for more tests, because if you're sick enough to be hospitalized, "the probability you have the disease is really high."

"It just goes to show you how desperate the situation is, though, that unless you can be hospitalized you're not going to be tested," he said.

One option to get tests

Stories abound about people who cannot get tested, even if they are sick. People who are asymptomatic but fear they have been exposedappear to assume that they shouldn't even try and get tested.

But Dr. Natasha Bhuyan said her company, One Medical, is trying to address that need.

The company, an outpatient primary care concierge service that normally costs $199 a year, is offering free memberships for 30 days that allow patients to get same-day new coronavirus tests, said Bhuyan, the company's regional medical director for the West Coast.

One Medical has so far tested about 500 people at a drive-up location in Scottsdale — an average of about 100 people per week — and has the capacity to test 200, she said.

In addition to testing people with mild symptoms, One Medical is testing people with no symptoms if they believe they have been exposed to COVID-19, said Bhuyan, a clinical assistant professor at the University of Arizona College of Medicine-Phoenix.

Patients need to consult with a clinician at One Medical before they can be tested, she said. (Patients can go to onemedical.com or download the One Medical app to sign up.)

"In the beginning, we were only testing patients with narrow symptoms like cough, fever, shortness of breath," she said. "And since then, we've learned that COVID-19 can present ... as a range of symptoms, diarrhea, loss of smell."

The company wants to test people with these and other symptoms like fatigue and body aches, Bhuyan said.

"In addition to that, we're also testing people without symptoms. I think this is a big change and it needs to be much more widespread in Arizona," she added.

She said testing asymptomatic people is important from a public health perspective because it provides more information about how it's transmitted, which is vital because there is a significant asymptomatic spread of COVID-19. And those who test positive can isolate themselves and health authorities have the ability to do contact tracing on them, she said.

One Medical also wants to test essential workers as well as the general public, she said.

"We do want to make sure that we reach the general public as well, because we know everyone's lives have complexity," Bhuyan said. "You might have a child with asthma. You might be taking care of older parents. And it helps to know if you have it or not."

Contact reporter Rob O'Dell at rob.odell@arizonarepublic.com or on Twitter @robodellaz.