By Steve Gorman and Nathan Layne
(Reuters) - Troubling spikes in coronavirus infection rates were reported on Friday in several U.S. states, mainly in the South and West, a day before President Donald Trump was due to preside over an Oklahoma campaign rally that will be America's largest indoor gathering in months.
Wall Street jitters over a resurgence in COVID-19 cases as states moved to reopen long-stifled commerce and ease social-distancing measures helped drive down major U.S. stock indexes, reversing earlier gains.
Experts say expanded diagnostic testing accounts for some, but not all, of the growth in cases - numbering at least 2.23 million nationwide on Friday - and that the mounting volume of infections was elevating hospitalizations in some places.
"Clearly the cases are rising rapidly. It's not just a matter of testing more," said Dr. Murtaza Akhter, an emergency room physician at Arizona hospitals, noting the lag time between a positive test and severe illness or death. "The real concern is what is coming up for us in the next week or two."
He said the latest wave of cases has put Arizona's major hospitals at or near capacity, and placed the Southwestern state on track to surpass New York at its peak on a per-capita basis.
More than 119,000 Americans have perished from COVID-19 to date, according to Reuters' running tally.
Particularly alarming has been the upward trends several states are reporting in the percentage of positive tests among individuals who are screened, a metric experts refer to as the positivity rate.
The World Health Organization considers positivity rates above 5% to be especially concerning, and widely watched data from Johns Hopkins University shows 16 states with average rates over the past week exceeding that level and climbing.
Four were averaging double-digit rates - Arizona at 17%, Alabama at 12%, Washington state at 11% and South Carolina at 10%. The dozen others were led by Utah, Texas, Mississippi, Florida and Georgia, all averaging rates of 7.5% or higher.
Some of the latest daily figures were also disconcerting.
Arizona, where doctors and public health administrators have called for making face coverings mandatory in public, reported a record 3,246 new infections over the previous 24 hours, nearly twice those tallied on Wednesday. Its latest single-day positivity rate, from Thursday, stood at 18.6%.
In Phoenix, where the president is due to visit a church next Tuesday for a "Students for Trump" event, the city council voted at the mayor's urging on Friday to mandate face coverings in most public places. That move came two days after Governor Doug Ducey issued an executive order allowing cities and counties to require face coverings.
Florida, one of the last states to impose stay-at-home restrictions and one of the first to begin lifting them, reported 3,822 new cases, a daily record. Its latest positivity figure was 10%, according to the state's health department.
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"The situation in Florida and Arizona is really concerning," William Hanage, an epidemiology professor at Harvard University, adding that the spike in cases was not just due to more testing but indicative of an "underlying outbreak of unknown size."
Even if the growth in confirmed cases partly reflects transmission among younger people less likely to be hospitalized, those people could infect the elderly and other vulnerable individuals with underlying health conditions.
"The more community transmission there is, the larger the risk that it infects somebody who is vulnerable. There are quite a lot of old people in Florida and in Arizona," Hanage said.
Another focus of concern was in Oklahoma, where the Trump campaign will hold a rally on Saturday at a 19,000-seat indoor arena in Tulsa, his first such event since lockdowns were imposed across much of the country in March.
Public health experts have warned that assembling thousands of shouting, chanting people inside the BOK Center and an adjacent convention hall poses the risk of creating a "super-spreader" event for the highly contagious coronavirus.
Rally organizers plan to hand out masks and hand sanitizer to attendees before they enter the venue, but they will not be required to maintain social distancing or wear face coverings. They also must sign a waiver promising not to sue Trump or the campaign if they contract the virus.
Trump supporters began lining up outside the arena well in advance. One of them, Randall Thom, 60, from Lakefield, Minnesota, said on Friday the United States needed to reopen.
"We can't be afraid of this China virus or whatever you guys want to call it. I'm not afraid of it at all," he said. "And I am so honored that President Trump wants to do a trade for us as citizens, you know, to give us our rights to be normal again."