TUCSON, Ariz. (CN) — Arizona’s Covid-19 reproduction number — a measure of whether a disease is spreading or contracting, also called R0 — is the lowest in the nation, by one count, just eight weeks after the state was in headlines as a coronavirus hot spot.
Governor Doug Ducey announced the achievement in a Facebook post Monday, citing rt.live, which ranks states based on numbers compiled by The Atlantic. The Grand Canyon State’s R0 (pronounced R-naught) of 0.76 means in broad terms that the disease is contracting in a state where 4,771 people had died from the illness as of Monday.
But University of Arizona epidemiologist Dr. Purnima Madhivanan urged caution at the R0 news.
The Arizona Department of Health Services counts only electronically transmitted test results — excluding thousands of Covid-19 lab reports submitted via fax. That should raise an eyebrow at the state’s reproduction number, Madhivanan said.
“If almost 25% of your tests are being thrown out, you don’t know many are susceptible and how many are infectious,” she said.
The R0 is a representation of a disease’s contagiousness. It’s a calculation, based either on models or data, of how many people will get a disease from an infected person, Madhivanan said.
With a reproduction number of 1.0, a disease would stay stable and become endemic. Anything above 1.0 can lead to a pandemic or epidemic. The goal is to get and keep the number below 1.0, meaning each infected person is infecting less than one person, she said.
“That means it is slowing down,” she said. “It doesn’t matter if it is 0.9 or 0.6 or 0.2. It really doesn’t give you that much more information. All you’re trying to do is get the R0 below 1.”
If the underlying data is accurate, keeping the reproduction number below 1.0 means the pandemic would eventually die out, Madhivana said.
In a weekly Covid-19 news conference Thursday, Ducey noted that hospitalizations are down in recent weeks, leaving hospitals at 80% capacity.
The positivity rate among tests has dropped from 8% to 6% in recent weeks, and the number of hospital beds occupied by Covid-19 patients is the lowest since May, Ducey said, adding the improvements are a direct result of Arizona residents.
“They’re doing the fundamentals — wearing masks, washing their hands, physically distancing, staying home when sick, and just using good old-fashioned common sense.” Ducey said.
Ducey, a Republican and an ally of President Donald Trump, thanked the administration for help during the pandemic.
He singled out the Federal Emergency Management Agency, which over the summer partnered with state health officials on testing and more recently, after a Trump executive order, boosted unemployment benefits by $300 per week for almost 400,000 Arizonans.
“We’re grateful for the president for taking this action, and we urge Congress to step up and provide certainty and clarity by extending these benefits,” Ducey said.
Arizona remains partially shut down.
Restaurants are open with reduced seating capacity, but bars are closed. Public water parks remain closed, but resort water parks are open — some selling day passes to non-staying guests. Some gyms have reopened, though most have not. The Department of Health Services will continue to review plans for individual businesses that apply to reopen, Ducey said.
“We want to have a consistent process, but I think anyone that’s frequented these places knows how different each situation is,” he said.
Ducey urged Arizonans to keep their guard up and stay vigilant.
“We are not taking a victory lap,” Ducey said. “This is not a celebration. This is a highlight on what’s working and an ask that we keep doing what works.”