Care home managers are "exhausted" and fear the escalating challenges in the weeks ahead as cases of Covid-19 soar, a committee has heard.
MLAs have been told that care home staff are at the "end of their tether" over concerns they cannot cope with a second wave of coronavirus in facilities.
The number of care homes dealing with an outbreak of cases has almost doubled to 84 in the last week.
More than 430 nursing home residents have died from Covid-19 since March, figures show.
Rita Devlin, from the Royal College of Nursing (RCN), said: "Managers in our care homes say they are at the end of their tether. They are exhausted and fearful and each day brings different and new challenges for them that they aren't sure they can maintain."
She said there are also issues with testing and that it puts a huge administrative burden on staff.
"There are patients with cognitive issues who don't consent to testing, and if you tried to test a patient without their consent that could be deemed assault," Ms Devlin added.
"In 2015 the RCN wrote a paper raising concerns of viability of nursing homes with difficulties with staffing problems and that has not improved. It has got worse.
"Management is concerned about their ability to cope in a second wave.
"We have a support system set up in care homes and we are reliant on the trusts to come and support us where there are shortages of staff.
"One care home had 22 staff not available because of isolation and sickness.
"Although trusts are trying to help, the difficulties remain and are increasing by the day."
John Patrick Clayton, from Unison, said said the number of cases are increasing at a "significant and worrying" rate.
"There has been a significant impact of Covid-19 in nursing homes and that causes us real concern," he told the committee.
"It's important that as the health service finds itself in a second wave, there has been a lot of focus on acute hospitals but the one thing that is clear is that Covid-19 has a massive impact on care homes and it needs serious attention.
"Before Covid-19 there were serious concerns about the state of our care sector that was related to a number of issues.
"These issues were to do with staffing as well as pay and terms and conditions. The Power to People review in 2017 identified that workers in the industry are underpaid and exploited by the system.
"We have seen concerns come to fore about viability of care homes."
Health committee chairman Colm Gildernew said that there is a sense of "deja vu" of the very worst days of the pandemic.
The Sinn Féin MLA paid tribute to the courage of nursing home staff, adding that care homes are facing another difficult time ahead.
Ms Devlin also said that some staff are expected to travel to work for a fortnightly Covid-19 test on their days off.
She warned that the suggestion of introducing a weekly test would create a "huge burden" on care home workers.
