More than a month after shipments of a promising new COVID-19 treatment started arriving in Minnesota, most of the doses haven't been used even though doctors initially feared demand would far outstrip supply.

State health officials say some medical centers have reported a surprising lack of patient interest in the outpatient antibody therapy, which might help people avoid hospitalization, but requires an hourlong infusion. Health systems also have struggled to create a process for providing the treatment, since resources have been stretched thin as they treat COVID-19 patients and administer coronavirus vaccines.

Still, there is hope that demand will pick up soon along with expanded operations at infusion centers — Allina Health System launched its program in late December and plans to double capacity in the coming weeks.

"When I signed on as the lead physician for this, I said: 'This is going to be like a floodgate — I will have like thousands of patients wanting it and I'm going to fall short,' " said Dr. Venkat Iyer, medical director for medical specialties at Allina Health Group. "… Right now, we have enough supply to give it to people. And the main bottleneck is our capacity to give it — capacity and staffing."

The treatment consists of laboratory-made antibodies that are infused in patients and designed to block the pandemic virus from attaching to and entering human cells. The federal government is funding the monoclonal antibodies, which are manufactured by two drug companies. President Donald Trump received one version when he tested positive for COVID-19 last year.

The state Health Department says that as of Jan. 5, patients had received just 1,652 infusions out of a statewide supply for 12,448 treatments, a usage rate of 13%. Nationally, only about 20% of available treatments have been infused, said Dr. Sarah Lim, a medical specialist with the Minnesota Department of Health.

"It's been relatively low, but it's increasing," Lim said of demand. "What we're hearing anecdotally from health care systems is that while, in the beginning, they had a lot of patients decline the infusions … they're starting to see the acceptance rate tick upward."

Early-stage treatment

The treatment is an option only for patients at increased risk of serious illness due to their age or health history, and their symptoms must be mild or moderate. That's been a problem in generating interest, doctors say, since patients offered treatment sometimes question the need for it since they're feeling pretty good.

So far, the state has shipped supplies to 88 infusion centers, 55 of which are up and running, said Alexandra Waterman, the Health Department's medical surge coordinator. Across infusion centers in the Twin Cities — where hospitals were hit by a wave of COVID-19 patients in November and December — about 2% of the treatments have been used.

With COVID-19 cases and hospitalizations declining in Minnesota, Waterman said more facilities might come on board. "With that, they'll be able to also help us with the messaging of: This is out there and this is where you can come to get it."

She added: "I think there just hasn't been a lot of public interest because they don't know [about it]. … Everyone is so focused on the vaccine right now."

Still some skepticism

On Saturday, Minnesota reported 2,489 new coronavirus cases and 43 more deaths due to complications of COVID-19. Although the seven-day rolling average for new cases has been trending up over the past week or so, new infections, deaths and hospitalizations have been well short of peaks in November and December.

Trump's usage of monoclonal antibodies raised the profile of the treatment, but not everyone is a believer. The risk of side effects is low, doctors say, but medical societies have not deemed the treatment as the standard of care for COVID-19 patients, stressing that more information is needed about potential benefits.

At Bloomington-based HealthPartners, clinicians can connect patients to treatments offered through a CVS Health program, but the evidence so far shows the therapy "hasn't been a home run when it comes to preventing hospitalization and death," said Dr. Mark Sannes, an infectious disease specialist. The numbers support "skepticism," Sannes said, although he noted that studies are ongoing.

If the treatment proves effective, "we'll embrace it and probably incorporate it into our treatment algorithms," he said. "I just don't think we're there yet."

Doctors at Mayo Clinic, however, have been "very satisfied and happy with results so far — very promising," said Dr. Raymund Razonable, an infectious disease specialist overseeing the clinic's program for monoclonal antibodies. Across its operations in Minnesota, Wisconsin, Arizona and Florida, Mayo has provided 2,200 treatments so far, and hopes to soon publish data about the impact on hospitalizations, intensive care usage and deaths, Razonable said.

At this point, monoclonal antibodies in Minnesota are not a scarce resource, said Razonable, who called demand for the treatment at Mayo "steady."

To be effective, the antibody treatment must be administered within 10 days of symptom onset. That's a challenge, doctors say, since clinics must quickly identify eligible patients among those testing positive and then provide education. The treatment is being provided under an emergency use authorization from federal regulators.

Rationing plans

Working under the initial assumption that supplies would be scarce, health systems developed plans to ethically ration treatment access by randomly selecting patients to receive it. But low demand at the University of Wisconsin has kept doctors from having to do so, said Dr. Peter Newcomer, chief clinical officer at UW Health.

As the availability of hospital beds dwindled late last year, health care workers pushed to provide the treatment, hoping that they could keep roughly 1 in 20 patients from being hospitalized, Newcomer said. But doctors need better data on which high-risk patients eligible for treatment are most likely to benefit, said Dr. Andrew Olson, medical director for COVID-19 Hospital Medicine at M Health Fairview.

The logistical challenge of providing the treatment would be considerable "even if there wasn't a pandemic," Olson said. Fairview opted to create a new infusion center just for COVID-19 patients, since others who need infusion treatments are particularly vulnerable to the coronavirus. After providing the therapy, health care workers typically watch patients for an hour in case of side effects.

"If we were able to generate the demand the government hoped for with monoclonal antibodies, you'd have to generate a different solution for how that many patients would receive treatment," Olson said. "This would take funding and collaboration on a different scale than we have seen so far."

Christopher Snowbeck • 612-673-4744 Twitter: @chrissnowbeck