Minnesota hospitals are moving away from forcing front-line workers to reuse N95 masks during the COVID-19 pandemic as the nationwide supply of the face-worn air filters increases.

Hospital nurses are seeing more N95s available at work, two officials with the Minnesota Nurses Association (MNA) said. Yet while there are more masks in the state today than a year ago, the demand remains great.

Minnesota hospitals collectively have about 2.8 million N95 respirators on hand, a supply that would last five months at the estimated burn rate of about 19,000 a day. A year ago, they had only enough to last two months, state data show.

"I won't be happy until we're back to optimal standards. And that means pre-COVID standards, where every patient (in medical isolation) has a box of N95s on their isolation cart," said Mary Turner, an ICU nurse and MNA president. Supplies in an isolation cart are only for the patient in isolation.

Tight-fitting N95 respirators are designed to protect the wearer by filtering out particles carrying pathogens such as the SARS-CoV-2 virus. The masks are designed to be used once and disposed. When COVID-19 hit last year, hospitals didn't have large reserves, leading to spikes in demand that outstripped global production capacity.

Acute shortages ensued. Crisis strategies came into play, such as decontaminating and reusing respirators for 10 days or more, leading to what Turner described as tremendous fear and anxiety among front-line workers trained to discard used masks.

Through a combination of stepped-up domestic manufacturing and new suppliers, the number of N95s in the U.S. is now great enough that federal agencies say the most extreme mask-preservation strategies no longer need be followed.

The Minnesota Health Department (MDH) says hospitals in the state are seeing sustained improvements.

"Almost all hospitals report being able to maintain their N95 supplies and have sufficient N95s on hand," MDH spokesman Scott Smith said. However, he added, "with the recent upswing in cases there are a small number who report they are not able to maintain the N95 supplies."

At Duluth-based Essentia Health, the supply of N95s is considered adequate thanks to "proactive" purchasing measures and past reprocessing of used respirators: "The reason we have adequate supply is because we, as well as most health care systems, were able to gain ground on inventory by decontaminating N95s, not because the supply was good or has improved," said Brian Zuck, Essentia's supply chain vice president.

At Mayo Clinic in Rochester, supply-chain officials said obtaining N95s has become easier.

"Mayo Clinic has been cautiously de-escalating conservation measures as supplies allow, and is planning to move back to conventional N95 standards for N95s in the coming days," said Dr. John O'Horo, chairman of Mayo's task force on COVID-19 personal protective equipment. "We are very happy ... we can move back to conventional standards."

At Bloomington-based HealthPartners, front-line providers are transitioning to what a spokesman called conventional standards for N95s. Currently care providers are using one mask per shift in the hospital setting. The system has stopped using ultraviolet light to decontaminate the respirators.

"We currently have an adequate supply of N95 respirators in our facilities, and as market supply has improved, we are less concerned about sourcing these should we need more," spokesman David Martinson said.

COVID-19 case counts

Thirty people who work in acute health care or nursing homes in Minnesota have died from complications of COVID-19, though not all of those cases stemmed from workplace exposures, the state Health Department says.

State data show exposures at home or in social situations outside work are more likely to lead to a positive diagnosis than exposures to patients or residents for health care workers.

All told, the state has seen 579,235 confirmed or probable cases of COVID-19 since March 2020, including more than 41,000 in health care workers. The Health Department announced 1,713 new cases among all Minnesotans on Sunday.

The state has seen 7,160 deaths from the viral respiratory illness, including six announced Sunday. More than 1.97 million Minnesotans have completed vaccinations, which is 55% of the way to the state's vaccination target.

"We really do believe that the end of the pandemic is in sight, but we are not there yet," Minnesota Health Commissioner Jan Malcolm said last week.

On April 9, the Centers for Disease Control and Prevention rolled out updated guidance that removed some of the most extreme measures used to conserve limited supplies of N95 respirators.

One of the major changes is that, even in a crisis, decontamination and "bioburden reduction" systems should no longer be used on N95 masks. Also, the N95 should not be worn more than five times during a crisis-capacity shortage.

CDC guidelines

The move away from cleaning and reusing N95 masks stems from an increased domestic supply of the respirators, the Food and Drug Administration has said.

There are 530 models of N95 respirators approved by the CDC's National Institute for Occupational Safety and Health. However, "surgical respirators" remain on the FDA's device shortage list as of today.

Locally, Essentia, HealthPartners, M Health Fairview and Mayo Clinic have stopped using devices or chemicals to decontaminate single-use masks. On Friday, the FDA announced it granted a company's request to revoke its authorization for a program that used vaporized hydrogen peroxide to decontaminate masks.

When supplies are limited, but not at crisis level, the updated CDC guidelines say, "N95 respirators should be discarded immediately after being removed."

Meanwhile, 3M Co., the nation's largest domestic producer of N95 respirators, has ramped up U.S. production of N95 masks from 22 million per month before the pandemic to 95 million a month today.

"Current production in the United States is meaningful and adequate to meet the increasing demand that we see going forward," said Omar Vargas, 3M's global head of government affairs. "We think 95 million, plus all the other producers in the United States, is a robust number here in the U.S."

Joe Carlson • 612-673-4779