A Western Sydney aged-care facility has become Australia's second biggest cluster of coronavirus deaths, and its chief executive officer has warned more are on the horizon.

Sixteen elderly residents with COVID-19 have died at Newmarch House in Caddens and, as of May 6, 66 people at the facility — 29 staff and 37 residents — had been infected.

The crisis began when a carer showed up to work with a "scratchy throat" last month, but there has been a stream of dire developments since then.

How did it start?

The facility's operator, Anglicare, learnt one of its employees tested positive for COVID-19 on April 11.

The female staffer worked six shifts despite displaying mild coronavirus symptoms.

It was not the first aged care home in NSW to have a confirmed coronavirus case, and Health Minister Brad Hazzard pleaded with workers in the sector to stay home if they were feeling sick.

On April 18, a 93-year-old man became the first COVID-19 death at the facility and there have been regular fatalities since.

Despite introducing infectious disease specialists to work with the centre, the situation appeared to be deteriorating.

"We do anticipate more deaths, yes," Anglicare chief executive Grant Millard told ABC News.

What has happened since?

Mr Millard says the nursing home has become a "pseudo-hospital" since it began quarantining its residents, but for a time its resources were stretched.

At one point, more than 60 of its staff were on paid leave either because they contracted the virus or had been ordered to self-isolate at home.

The the state's chief health officer Kerry Chant reported the carer who introduced the bug to the facility was "absolutely mortified" about the situation.

Date Deaths Description April 18 1 93-year-old man April 19 1 94-year-old man April 21 1 92-year-old woman April 23 1 78-year-old woman April 24 1 96-year-old woman April 25 1 82-year-old man April 27 1 89-year-old woman April 28 4 91-year-old woman 93-year-old man 90-year-old woman 89-year-old woman April 29 1 77-year-old man May 2 1 76-year-old woman May 4 1 72-year-old man

Mr Millard made desperate pleas to the Federal Government to help with staff shortages, and it has since been offered "unlimited workforce support" by the Commonwealth.

In early May, Mr Hazzard said several of the workers have recovered and were returning back to the facility to continue to provide care for residents.

Mr Millard said the workforce was operating at an "extremely high level for a residential aged care facility" with almost two dozen registered nurses, 25 carers, 11 cleaners and other visiting medical specialists.

An infectious disease expert was also on site and staff were being tested for COVID-19 daily and on May 2, authorities said it was investigating potential breaches of infection control.

There are almost 80 residents still in the facility, but tensions have erupted between their families and Anglicare.

Flowers were left outside Newmarch House at the weekend. ( AAP: Joel Carrett )

Why are they unhappy?

Family members claim Anglicare's communication has been inadequate, say they feel "frustration, disappointment, anger and desperation" about that.

Some were also concerned about the quality of care, with one man complaining his mother fell in the shower and didn't receive help for at least 10 minutes.

At least one relative, Matthew Fowler — who described the situation there as a "black-box" — lodged a formal complaint with the NSW Aged Care Quality and Safety Commission.

Relatives were also desperate to take their loved ones out of the facility, which NSW health authorities have allowed, but were finding it difficult to house them with adequate care.

Resident Lionel Fowler, 87, was happy in self-isolation but his son Matthew worries about him. ( Supplied )

In a letter to Mr Millard, a group of the 94 relatives and friends of residents claimed they had learnt of important developments at the facility through media reports, and that phone calls were going unanswered.

The letter made several demands of Anglicare, including increased visitation capacity for family members and the establishment of a hotline so relatives could receive better updates.

The NSW Premier Gladys Berejiklian said on April 29 she was aware of the letter and that her Government had issued a please explain to the Federal Minister for Aged Care, Richard Colbeck.

What's happening next?

Mr Millard said the family's requests were "completely reasonable" but defended the centre's handling of the outbreak.

He said he was holding daily conferences with state and federal governments about the situation.

"Obviously there are tensions at the moment and I guess a difference of opinion, to a certain extent, about how some things should be handled," he said.

The CEO said staff had distributed mobile phones to every resident and that people had been brought in to the facility to set up video calls.

Window-visits were also introduced shortly after Mr Millard received the letter.

Still, the CEO said the situation was "sincerely regrettable" and hoped the family and public could appreciate the complexity of the outbreak.