A nurse treating patients with the novel coronavirus says red eyes may be a sign that someone is infected.

Chelsey Earnest, a worker at the Life Care Center in Kirkland - the epicenter of the outbreak in Washington - told CNN that the eyes were 'the single most important' sign that residents had COVID-19, the disease caused by the virus.

'It's something that I witnessed in all of [the patients],' she said.

'They have, like...allergy eyes. The white part of the eye is not red. It's more like they have red eye shadow on the outside of their eyes.'

Chelsey Earnest (pictured) is a nurse who treated coronavirus patients at Life Care Center in Kirkland, the epicenter of the coronavirus outbreak in Washington state

She said redness around the eyes was the most important sign that someone was infected with the virus. Pictured: Medics transport a patient through heavy rain into an ambulance at the Life Care Center, March 7

Earnest said that if she told one physician that somebody had red eyes, a hospital bed would be made ready for them. Pictured: Sisters Carmen Gray (reflected at left) and Bridget Parkhill visit their mother Susan Hailey, who is recovering from coronavirus at Life Care, March 24

The Centers for Disease Control and Prevention (CDC) doesn't have red eyes - or any eye issues - on its list of symptoms.

What is included are fever, cough and shortness of breath. Persistent pain or pressure in the chest and bluish lips are listed as emergency signs.

But the American Academy of Ophthalmology sent an alert on Sunday about reports that the virus can cause conjunctivitis, which is inflammation of the membrane that lines the eyelid.

Earnest said patients at Life Care Center often would go from having no other symptoms but red eyes to dying.

'We've had patients that just had the red eyes as the only symptom that we saw and go to the hospital and pass away,' she told CNN.

'I've even had the disaster medical control physician say: "Do they have the red eyes?" And I will say: "Yes."

'And he'll say: "I'll find you a bed." It's just something about this, the way that it affects these patients.'

Life Care Center, which is located outside Seattle, has been one of hardest hit from the virus since the first cases were detected in February.

Coronavirus deaths in the U.S. rose to 783 Tuesday evening; the numbers as of 7.30pm

As of Tuesday, at least 129 patients, staff and visitors were infected, according to the CDC and Life Care Center.

At least 35 people have died, 18 of them being patients.

Jeffrey Duchin, an officer for Public Health, Seattle & King County, said he asked hospitals to offer staff, but he was denied.

'I personally would have thought that we would have been able to muster more staff from our local healthcare system,' Duchin told KUOW.

'But I think everybody at this point was already experiencing some degree of COVID-19 stress, and didn't feel like they had staff that they could spare.'

In the US, there are more than 54,000 confirmed cases across all states and territories and more than 700 deaths.