It was late March, the coronavirus was spreading, people were still getting on planes to go on vacation, and flight attendants were posting on Facebook that yes, they had contracted the virus themselves.

A Frontier Airlines flight attendant said the question hit her: “We are still flying?”

“We are testing positive," she said, speaking on condition of anonymity to protect her job. "Something needs to be done.”

While the volume of passengers at U.S. airports has plummeted, one union representing American Airlines flight attendants offered a glimpse this week of the number of coronavirus infections in their ranks: About 100 flight attendants for Philadelphia’s dominant carrier have tested positive.

Confirmed cases will increase “without a doubt,” the union told members Monday.

Sara Nelson, president of a separate union, the Association of Flight Attendants, said Wednesday that at least 150 flight attendants at other airlines have tested positive for the virus.

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“We believe that that is underreported,” Nelson said in a video message to her members. At least 1,000 flight attendants are in self-quarantine because of exposure to the coronavirus, she said.

One Philadelphia-based flight attendant who tested positive died last month: 65-year-old Paul Frishkorn, who worked for American.

“Anxiety levels are at an all-time high,” said Julie Hedrick, national president of the Association of Professional Flight Attendants (APFA), which represents 27,000 American Airlines workers.

Those worries are highlighted in posts to private Facebook groups where flight attendants have shared stories of getting the “dreaded” phone call about a passenger they flew with testing positive, or having to quarantine alone in a hotel.

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Others have lamented how hard it is to get tested, even for flight attendants, who are considered “essential” workers during a crisis that has shut down wide swaths of the U.S. economy. Some are angry about cheap airline tickets that tempt passengers to fly unnecessarily during a global pandemic.

Then there’s the larger uncertainty that is becoming a hallmark for workers still on the job as the virus spreads: As the Frontier flight attendant put it: “Every day, every flight that you take, you don’t know if this is the day you’re going to get it.”

Both the Frontier flight attendant and a second who asked that her employer not be identified said they’d like to see more flights grounded, and employees told to stay home, during the pandemic.

The Frontier flight attendant acknowledged it’s a divisive topic in group chats with colleagues. “Some people are just so concerned about the job and the money,” she said. And some are worried “about their health, about their families, about their children.”

“Flight attendants might be sick and not know for days," said Hedrick of the APFA. "In the meantime, they continue to work and then return home to their families.”

In its message to members on Monday, the union said American’s response to coronavirus has been “reactive” rather than proactive, and that the company “repeatedly downplayed” the union’s concerns, first raised in January.

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Hedrick said the APFA has consistently advocated for access to personal protective equipment, social distancing on planes, and taking temperatures of passengers and crew in airports.

Last weekend, American told flight attendants the company will start providing masks and that front-line employees are also allowed to use scarves and bandannas as face coverings. American has also limited food and beverage service on flights through April 30 and is blocking off “50% of standard middle seats and all seats adjacent to flight attendant jump seats,” a company spokesperson said.

Flight attendants are eligible for a two-week “paid pandemic leave” if they test positive, are waiting for test results, or are told to quarantine by a doctor or health officials. Some employees are also eligible for voluntary leave with a partial salary, the company said.

“The safety of our customers and team members is our top priority,” American said in a statement. “We are in close contact with the Centers for Disease Control and Prevention and public health officials, and are coordinating with them on any required health and safety related measures. We continue to look at all ways we can care for — and protect — our team during this stressful time.”

Frontier said it has given masks and gloves to all flight attendants, implemented a system to monitor for potential coronavirus exposure, and offered voluntary leaves with partial pay. The airline said it had increased “heavy cleaning” of planes, and recently started using a fogging disinfectant to kill viruses on surfaces.

A Frontier spokesperson also pointed to a change this week: Passengers are now required to certify that they have not exhibited symptoms of the coronavirus in the last 14 days, that they will check their temperature before going to the airport, and that they won’t travel if they have a fever.

“We have standing scheduled calls with the Association of Flight Attendants three times a week and sometimes more, if needed, so that we can communicate on and react to any specific concerns that are being raised by flight attendants,” Frontier said in a statement.

Meanwhile, unions are decrying unnecessary flights. The Association of Flight Attendants, which represents 50,000 employees at 20 airlines, has called for a halt to leisure travel, while allowing flights that support essential services to continue.

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Hedrick agrees. “Transporting medical personnel and supplies” by plane is necessary, she said, “however, leisure travel and more flights than absolutely needed at this point puts our flight attendants at continued risk, and does not help with the containment of the virus.”

Frontier said it will not be operating “the vast majority of our original flight schedule for the month of April.”

A spokesperson for the Federal Aviation Administration did not directly respond to questions about whether the U.S. Department of Transportation is considering limits on leisure flights. The agency referred to guidance for airlines and flight crews, issued March 12, that gives advice on self-monitoring for symptoms, practicing social distancing during layovers, and using private transportation between airports and hotels.

“We have some flight attendants who are very sick right now,” Nelson said Wednesday. “And they need our support. They need our good thoughts and our prayers, and they also need us to listen to them, that we need to take this very seriously.”