Rumors about the manager with the virus started to spread around Worldport, UPS' sprawling air hub in Louisville, Kentucky, earlier this month. Employees texted one another to ask whether they'd heard about Roml Ellis, the well-liked 55-year-old who worked the night shift. They'd heard he was sick, that he'd been hospitalized and then that he'd died.

UPS employees said that despite asking management repeatedly about their sick co-worker, they were kept in the dark as the company cited medical privacy concerns. On April 6, in response to a question from reporters, Kentucky Gov. Andy Beshear confirmed that a UPS employee had died from COVID-19, the disease associated with the coronavirus. On Friday, after rumors began to fly between workers online, UPS announced that a second employee had died.

"It was all hush-hush," said a Worldport employee, one of more than two dozen delivery workers interviewed for this story who asked that their names be withheld for fear of losing their jobs. "The only reason we got the full details was because it was reported on the local news station."

As the coronavirus spreads through the ranks of the nation's delivery workers, employees and union representatives across the country said there has been a frustrating lack of communication with front-line employees about coronavirus cases from UPS and FedEx. Employees and union officials said that has bred fear and anxiety among more than 600,000 "essential workers" at the country's two largest corporate delivery companies.

A FedEx worker unloads packages from his delivery truck in Washington, D.C., on March 31, 2020.

At least three delivery workers have died from COVID-19 within the past week.

FedEx confirmed the death of one of its pilots. UPS said two employees at the Worldport hub have died within the last week, although a spokesperson declined to confirm their causes of death. Beshear confirmed that the first was linked to COVID-19, and the second death was also due to the virus, according to four employees and an internal UPS document provided to NBC News.

Neither FedEx nor UPS would say how many employees had been diagnosed with or died from COVID-19. FedEx said employees had been diagnosed "across the enterprise." UPS employees and union representatives said they had heard of confirmed cases in more than a dozen states.

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UPS and FedEx have been touting their roles in the federal response to the pandemic. Both are participating in Project Airbridge, a new operation run by the White House's coronavirus task force to help distribute medical supplies across the country to help fight COVID-19.

But workers said their employers' refusal to share crucial information is leaving them vulnerable in their workplaces.

"How are any of us supposed to get ahead of a virus when we don't even know who's sick?" a Worldport employee asked.

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As much of the country remains shut down, delivery workers have become even more vital, delivering food, medication and cleaning supplies to medical facilities and households across the U.S.

But as with many hospitals and the federal government, the swift spread of the virus caught the delivery industry on its heels. In recent weeks, the companies have scrambled to adjust, creating leave policies, figuring out how to practice social distancing and trying to find and distribute protective equipment and cleaning supplies.

Workers at both companies said they have begun to be provided masks, gloves and cleaning supplies. However, they said many are still working in close proximity — in the bellies of planes, in delivery trucks and in warehouses — and want to know whether their co-workers are sick so they can keep themselves and their families safe.

"We don't want to know people's names, but we do want to know if we were working in direct contact with somebody who's contagious," said a longtime UPS employee who works at the Worldport facility. "All we get from the supervisors is 'the only thing we know is what management tells us.'"

Workers at Worldport said that they received masks only the day after news of Ellis' death broke and that areas of the facility where about 11,000 people work are still not disinfected consistently. (Ellis' family members didn't respond to requests for comment.)

Less than a week after Ellis died, UPS announced that a second employee, who had been absent for 10 days, had passed away with COVID-19, according to four employees and a copy of the announcement provided to NBC News.

Citing its privacy policy, UPS declined to confirm the cause of death of the second employee, which was first reported by WDRB-TV of Louisville. But the company told NBC News that the health of its employees is a top priority.

"We are vigilantly taking steps to protect the health and welfare of our employees, customers, and the general public," spokesman Matt O'Connor wrote in an email.

The company said it alerts co-workers who may have come in close contact without disclosing the workers' identities and works with health officials to trace any potential spread. It also said that it makes sure to "clean and disinfect the work areas where that employee worked according to public health department recommendations before work resumes" and that it has increased disinfecting at its facilities generally.

O'Connor added that UPS informs local unions when a case is diagnosed but not all workers onsite, "as this is beyond the scope of guidance provided by public health officials."

Union officials in New York, Philadelphia and Arizona said they aren't always being told of cases, leaving their members feeling tense and vulnerable, including in areas like New York, the center of the pandemic.

"I don't know how they can say they're communicating when they are not," said Lou Barbone, a business agent with Teamsters local 804, which represents UPS workers in the New York City area. "The stewards don't know. I don't know. Members don't know."

"A lot of members are grateful to have jobs," Barbone added. "They're just genuinely concerned about their health and their families."

UPS said it has daily calls with labor representatives and informs them of cases at the facilities they represent. "We encourage union leaders who claim not to be receiving information to discuss this with their respective UPS labor relations representatives," O'Connor told NBC News.

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Workers at FedEx said there's a similar lack of communication. At a Minnesota facility, for instance, two employees on different shifts said one was informed about a positive case in the building while the other wasn't.

"To be quite frank, there aren't any policies in place," said a manager for FedEx Ground in Nashville, Tennessee, who spoke on condition of anonymity for fear of retribution. "Every time any one of us brings up a concern about how to make the workers safer ... it's always a matter of 'oh, let's run this up the chain.'"

FedEx's structure poses an additional challenge. An estimated 100,000 employees who deliver around the country for FedEx Ground are employed through a network of contractors, in addition to the estimated 200,000 people the company employs directly. Those contract employees often don't get health insurance or sick leave through their jobs, and while FedEx may inform the contractor when someone comes up positive, the information may not move down the chain.

"There's no communication about what to do if you're sick," said a FedEx Ground driver in the Kansas City, Missouri, area. "No mention of if we'll still get paid if we get sick."

A FedEx spokesperson told NBC News that "the safety and well-being of our team members and customers is our top priority." The company said it has bought and distributed millions of masks and is "actively promoting social distancing on the job," including changing work processes where possible.

But package handlers who move thousands of boxes a day said it's virtually impossible to stay 6 feet apart. Some worry that it will only get worse as FedEx hires more people to keep up with growing demand sparked by the pandemic.

"We're pushing more people into the same space with no measures to protect the people we have working there now," the Nashville manager said. "It's like sardines in a can."