More COVID-19 patients are expected to receive convalescent plasma therapy since the Trump administration issued an emergency authorization Sunday, backed by research from the Mayo Clinic in Rochester.

"This makes it simpler for hospitals to get access to convalescent plasma," said Dr. R. Scott Wright, a coordinator of Mayo's national plasma program.

The treatment involves a transfusion of blood plasma from someone who has recovered from the new coronavirus into a newly infected patient with the hope that the antibodies in the plasma will prevent complications and speed recovery.

It is a concept that has been used for more than 100 years in infectious disease treatments, with varying degrees of success.

But some in the medical and public health communities were critical of the announcement, citing a lack of rigorous evidence, unintended consequences of the decision and possible political pressure from the White House.

"In summary I would call convalescent plasma potentially promising but not the major breakthrough that it was billed as," said Dr. Howard Koh, a Harvard University professor and former health official in the Obama administration.

The U.S. Food and Drug Administration's decision to grant an emergency exception, which brings the treatment to the bedside before standard regulatory hurdles are satisfied, was made without the completion of any randomized clinical control trials to prove that the treatment improves outcomes.

"In a time of pandemic response where resources are finite, we need to focus our attention where the science is the strongest and the evidence is strongest," Koh said.

The FDA's decision could discourage enrollment in clinical trials, in which only half of the enrollees receive plasma while the other half receive a placebo. Treatment under the emergency-use order comes with certainty that patients will get the real thing.

"Our fear is that this will make it even harder to get people to enroll in those randomized clinical trials," said Dr. Jed Gorlin, a co-medical director for blood transfusion service at Hennepin Healthcare.

Doctors at Mayo, where the plasma research program has included more than 72,000 transfusions at nearly 2,800 clinical locations under a more limited FDA program, said that a randomized trial was not a goal of the study.

"We offered the FDA to convert this study to a randomized control trial," Wright said. "They said, 'Thanks for offering, we think there are a number going on right now.' "

Dr. Michael Joyner, Mayo's lead researcher for the program, said that even without a trial, the work at Mayo had produced enough evidence to clear the FDA's bar for emergency use.

"It seems like convalescent plasma checks all of those boxes — unmet medical need, evidence of minimal harm and suggested evidence associated with possible efficacy," he said.

Joyner added that plasma therapy was most effective when it was given to a patient who was severely ill but did not have a life-threatening condition. Additionally, they should receive the therapy three days after diagnosis and before they are in intensive care or on a ventilator.

With the FDA's order in place, Mayo announced Monday that it discontinued enrollment in its clinical study but will continue to follow study participants for at least another 30 days.

Two FDA emergency authorizations of the drugs remdesivir and dexamethasone, which have both been supported by clinical trial results, have helped hospitals improve COVID-19 treatment.

In Minnesota, hospitalizations have dropped significantly since reaching a peak of 606 patients three months ago. The Minnesota Department of Health reported that 310 were receiving hospital-level care, with 135 of them in intensive care units.

Daily reports of fatalities have also dropped from a high of 35 on May 28 to four reported Monday. About 74% of all fatalities have been among residents of nursing homes or assisted-living facilities.

A total of 1,771 Minnesotans have died of COVID-19 complications. Most have underlying health conditions that made them more susceptible to the disease, including heart, lung and kidney diseases.

After 717 newly confirmed COVID-19 cases were reported Monday, Minnesota passed the 70,000 mark with a total of 70,298 cases. However, not all infections in the state have been confirmed by a diagnostic test. There have been 1,386,513 tests processed.

State health officials are continuing to watch for infections stemming from the Sturgis Motorcycle Rally, where an estimated 450,000 people gathered over a 10-day period this month.

An additional five Minnesota cases linked to the rally were announced Monday, bringing the state's total to 27.

Kris Ehresmann, infectious disease director at the Health Department, said she expects more cases to develop among rally attendees and their close contacts.

The emergency approval of plasma therapy could also make it more difficult for hospitals to obtain the donated blood plasma.

"We will likely need more donors," Wright said. "We will need to encourage more people to donate."

So far, donations have met demand in the Twin Cities.

"We have always had inventory since early in April," Gorlin said. "If demand increases significantly that would be a challenge."

Hennepin Healthcare sent some of its plasma to hospitals in Texas, Florida and other states where hospitalizations had surged.

It is unclear how the FDA's decision will affect local hospitals, Gorlin said.

"The bottom line is the FDA makes a decision overnight and it takes us weeks to comply with all the specific requirements," he said.

Coming on the eve of the Republican National Convention and a day after President Donald Trump claimed, without evidence, that the FDA was responsible for vaccine and treatment testing delays, the emergency authorization of plasma therapy set off speculation that the FDA buckled to political pressure.

A New York Times report last week said that officials at the National Institutes of Health, including infectious disease expert Dr. Anthony Fauci, expressed concerns that there was not enough evidence to justify an emergency-use order for plasma therapy.

"When the President overtly and explicitly criticizes his own agency ... it confuses the public because he is talking about his own departments," Koh said. "In a crisis like this you are expecting government to be working together under the leadership of the White House."

Mayo said it was giving reports on its research several times weekly to the FDA.

"The FDA has been very silent on this and actually did not give us a hint, until the last day or so," Wright said.

Glenn Howatt • 612-673-7192