Dr Greg Macasaet, an anaesthesiologist in the Philippines, knew his time was up.

"If they intubate me and place me on a ventilator, then the game is almost over," he said in a text message to a fraternity brother.

He and his wife, Evelyn, also an anaesthesiologist, chose to stay at their posts as the first of the patients with signs of infections from the deadly coronavirus outbreak began to roll into their hospital, the Manila Doctors Hospital, one of the biggest in Manila.

Soon, both found themselves infected as well. Within days, Dr Macasaet's condition deteriorated.

His final thoughts were of his wife, who was also fighting for her life, and his son Raymond who has autism. "Raymond needs financial and emotional care for the rest of his life, something I may no longer be able to fulfil," he said.

By the time a bishop he asked for was alerted, Dr Macasaet had already been intubated. At 4am on Sunday, he died.

At least four more doctors at other hospitals have died after treating infected patients.

Two of them had dealt with the same patient who had lied about her travel history.

Healthcare workers on the front line of the war against the coronavirus are under siege. Patients are flooding hospitals, even as masks and other protective gear and hospital beds run out.

At least six doctors are in critical condition and over a thousand healthcare workers have been quarantined in Manila alone.

Hospitals across Manila, a city of more than 1.8 million people, can no longer cope with the number of confirmed and suspected cases which are growing by the day.

A top hospital administrator said most hospitals also do not have enough mechanical ventilators.

The largest and most well-equipped hospital has, at most, just 22 ventilators.

Even more critically, hospitals are running out of personal protective equipment, or PPEs, for their medical staff. A small hospital in Los Banos city, two hours north of Manila, was repurposing grocery and garbage bags and plastic water containers as PPEs.

The Medical City hospital, which has about 800 beds, said it had 18 patients on Monday who tested positive for the coronavirus.

Six had already been hooked up to ventilators, and five more were in critical condition.

"Unless we are able to move the new patients to other hospitals, our healthcare delivery system is going to break down," said its president Eugenio Jose Ramos.

St Luke's Medical Centre said its two upscale hospitals in Manila are treating 48 confirmed cases and monitoring 139 more who may have the virus.

Nearly 600 hospital staff, meanwhile, have been quarantined.

The Makati Medical Centre, another top hospital in Manila, can no longer take in any more patients.

It currently has 70 confirmed and suspected cases that include some of its doctors, nurses and nursing aides.

The Philippine Heart Centre is asking patients to go elsewhere.

"We have a lot of heart cases. These are all high-risk patients," Dr Joel Abanilla, the hospital's executive director, said in a radio interview.

A 2018 study showed that the Philippines had 101,688 hospital beds distributed across 1,223 hospitals.

If just 1 per cent of the country's population of roughly 107 million catches the virus, "it is easy to see how our hospitals will be quite easily overwhelmed", said Dr Ronnie Baticulon, an associate professor at the University of the Philippines College of Medicine, in a commentary for CNN Philippines.

Yet, most of the country's healthcare workers remain on the front line despite the risks.

At 64, Ms Alita Gonzales still goes to the Philippine General Hospital, where she works as a nurse, every day. She knows she's among the most vulnerable, given her age.

"But we took an oath," she said.