The World Health Organization said Tuesday that two of its workers have been diagnosed with the coronavirus as health care workers across the U.S. begin to test positive, prompting many on the frontlines to prepare for the likelihood of a long road ahead.

WHO spokesman Christian Lindmeier told Reuters that the staffers had left the office and once at home started to show symptoms.

At least 200 health care workers in Connecticut and New York were put on leave after possible exposure to COVID-19, Gov. Ned Lamont D-Conn., said Monday night.

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A health professional at the University of Southern California Medical Center in Newport has tested positive for the virus, according to the Daily Trojan. Meanwhile, two doctors in New Jersey and Washington state are in critical condition after being exposed to the virus. The World Health Organization said Tuesday that two of its staffers have coronavirus.

At UC San Diego Health, two health care workers were confirmed to be infected on Saturday and are currently quarantined, officials said, according to the Los Angeles Times.

"[The University] launched an extensive effort to identify any patients or health system colleagues who may have been in recent contact with either of the two health workers.” the paper said.

The Mount Sinai Health System in New York reached out to inform its patients in an email that it is "prohibiting all visitors across" the system starting on Tuesday — with certain exceptions.

"As the COVID-19 situation evolves, we at Mount Sinai Health System must take important steps to ensure the health of all of our patients, staff and local communities," the email said.

Only one visitor will be allowed at pediatrics/NICU, maternity, postpartum, end of life/palliative care, ambulatory geriatrics and emergency departments, the statement read.

Lamont said the 200 health care professionals possibly infected with COVID-19 in the Northeast are employed by Nuvance Health, an interstate health system in New York and Connecticut that services seven hospitals in the area.

"I'm losing nurses by the day," Lamont announced on MSNBC’s “All In With Chris Hayes” earlier on Monday night. He later clarified that they held different roles and were not all nurses, the Hartford Courant reported.

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A lack of testing has been a problem throughout the U.S., which is a reason the infected numbers as likely to be much higher than currently reported. It leaves officials and the public in the dark on how widespread the virus really is.

“If I can test those nurses, I can potentially get them back into the game a lot sooner,” Lamont told Hayes. “We’ve got a surge in use, demand is going up and I’m losing nurses by the day who have to furlough themselves for some time. That’s a priority for testing for me.”

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Doctors and medical staff are required to get up close and personal to treat the infected and limit the spread of the virus. Their continued exposure to the virus makes them susceptible to contracting it.

"This virus is dangerous, and its impact is still unfolding," American College of Emergency Physicians President William Jaquis said in a statement. "As emergency physicians, we answer the call to care for our most vulnerable, even at great personal risk. Knowing that, I urge each of you to meticulously follow the recommended precautions to protect yourself."

The recent shortage of N-95 protective masks is also worrisome for doctors, who need them to treat patients, U.S. Surgeon General Jerome M. Adams wrote on Twitter in late February.

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“They are NOT effective in preventing general public from catching #Coronavirus, but if health care providers can’t get them to care for sick patients, it puts them and our communities at risk!"