Researchers have found that nearly all coronavirus (COVID-19) hospitalised patients placed on mechanical ventilators in New York's largest health system have died.

For the findings, published in the Journal of the American Medical Association, the researchers examined the electronic health records of 5,700 patients hospitalised at Northwell Health, New York State's largest health system. Final outcomes were known for 2,634 patients.

They found that about 20 per cent of COVID-19 patients treated at Northwell Health died, and 88 per cent of those placed on ventilators lost their lives.

"To our knowledge, this study represents the first large case series of sequentially hospitalized patients with confirmed COVID-19 in the US," study authors.

This report describes the demographics, baseline comorbidities, presenting clinical tests, and outcomes of the first sequentially hospitalised patients with COVID-19 from an academic health care system in New York.

In the study, the research team revealed that the most common comorbidities were hypertension (56.6 per cent), obesity (41.7 per cent), and diabetes (33.8 per cent).

During hospitalisation, 373 patients (14.2 per cent) were treated in the intensive care unit care, 320 (12.2 per cent) received invasive mechanical ventilation, 81 (3.2 per cent) were treated with kidney replacement therapy, and 553 (21 per cent) died.

Mortality for those requiring mechanical ventilation was 88.1, the researchers revealed. The median postdischarge follow-up time was 4.4 days and a total of 45 patients (2.2 per cent) were readmitted during the study period.

"This study has several limitations. First, the study population only included patients within the New York metropolitan area. Second, the data were collected from the electronic health record database," the researchers noted.

The US continues to be the worst affected, with 841,556 cases and 46,688 deaths, the highest tallies in the world..