Police and firefighters never know what they'll face when they head out on a call, but the spread of the novel coronavirus has heightened that uncertainty and risk.

“Every call has the potential to be exposed to COVID,” said Robert VanZandt, who's worked for 12 years as a firefighter and paramedic in Belchertown. “We could be walking in, touching the same doorknob or even walking through the same hallway that someone coughed in while they were exiting the building, you know, we're being exposed.”

VanZandt is among the more than 200 Massachusetts firefighters who have tested positive for COVID-19.

All I was wearing was my uniform, simple mask and gloves," recalled VanZandt, who believes he was infected during a routine EMT call at a local hospital when he and his partner were led, by accident, into the COVID-19 area.

"We walked in there. I kind of took a quick 10 second look around and all I see are people on nebulizers and breathing treatments and so on," he said, "and I'm just like, 'Okay, now I'm in where everything is.'"

Rich MacKinnon, head of the Professional FireFighters of Massachusetts, representing firefighters, paramedics and EMT's, is calling for expanded testing for his 12,000 members.

“We could be asymptomatic carriers and that has been one of our fears from the beginning - is not only for the safety of our families — but we don’t want to be carriers of this, as we go from call to call from emergency to emergency," said MacKinnon. "We’re in people’s houses, we’re in, you know, buildings and we don’t want to be spreading this disease."

But right now, there’s still not enough testing for the general population. Governor Charlie Baker points to ongoing shortages of needed materials and recently said it’s a problem that states can’t solve on their own.

“The big issue is around the swabs, and the transport media, and the reagents. And again, there are people who are working on this one, but this is one where the federal government has the ability to put their foot on the accelerator.”

Baker said Massachusetts is now conducting between 8,000 and 10,000 tests per day, making it one of the top states in the country in testing per capita. But an analysis by the Harvard Global Health Institute found that that number still falls well short of what’s needed to safely reopen the state.

“Testing needs to be part of a comprehensive management strategy,” Dr. Jonathan Zenilman, professor of medicine at Johns Hopkins University School of Medicine, Infectious Disease Division.

And, Zenilman said, any strategy for getting back to normal should include not just coronavirus tests, but also antibody tests — blood screens that detect who has already been infected.

“The question, which hasn't been answered yet, although we do expect to have answers within the next couple of weeks, if not months, is whether antibody, presence of antibody, confers immunity,” Zenilman said.

After he developed fever and severe fatigue, VanZandt got tested at a first responders' priority testing center where he was given a nasal swab test. But, by that time, he’d already exposed his pregnant wife.

“I got my pregnant wife sick. That's, you know, the worst case.”

VanZandt’s wife, Nicole, is now recovering and said while they tried to keep separate and disinfect the house, she became resigned to the fact that her husband’s job put her at risk.

“I mean, it's virtually, I feel like impossible, if you're living in the same house with somebody to not get it,” she said.

For now, protective gear is still considered the best defense for first responders, but it’s still in short supply. VanZandt said that at his department, critical N-95 masks are reused up to five times.

And given the current shortfalls in protective equipment and testing, experts advise being aware of the early signs of a potential infection.

“If you have a cough or you have a low-grade fever, take yourself out of the workforce. Get yourself a test and stay home until you have the results of that test," said Rochelle Walensky, chief of infectious diseases at Massachusetts General Hospital. "That's what we're doing in health care workers and that's what I think we should be doing in first responders.”