The National Ambulance Service (NAS) is currently operating at "Level Three Red", which means it is under major pressure heading into New Year's Eve.
The NAS sent out urgent messages on Thursday afternoon asking for any available staff to work overtime and to cover up to 19 staff who are out sick in the greater Dublin and Leinster regions.
Extra crew members were needed to cover all areas on Thursday night. Shifts to be covered this weekend and into next week include Cavan, Drogheda, Ardee and Dundalk in Co Louth, Castleblaney in Monaghan, and Navan, Co Meath.
On Thursday the NAS was desperately looking for staff to help cover half-crews in Drogheda, Monaghan, Dublin South Central and Loughlinstown, while full crews were missing to cover Wicklow, Maynooth, Longford, Athlone and Ardee.
According to the HSE's own NAS Capacity Action Plan, Level Three means operational resourcing is between 10 and 15 per cent less than affordable capacity to meet demand. Between 10 and 20 per cent of red/amber calls will receive a response in one to two hours.
Level Three also means a loss of between 10 and 15 per cent of planned fleet levels.
One staff member said: "The service is at breaking point, even before Covid-19 hit a lot of staff.
"People aren't really interested in coming in to the job due to the pay and conditions and crews are blessed if they finish a 12-hour shift on time and not hours later. We are all burned out.
"One big thing needed is to educate people what an ambulance is for and when it is needed. Sometimes ambulances are used as a big yellow taxi which delays the service for real emergencies."
In a statement, the HSE said: "The National Ambulance Service (NAS) has a surge plan in place which represents a national approach to capacity planning intended to enable a consistent sector approach to patient safety, risk mitigation as well as system and resilience understanding at times of escalating pressure.
"It provides systems partners and stakeholders with a clear visual representation of the issues faced and actions being considered and taken. The plan has four levels of escalation.
"Today, in response to significant levels of demand, which is also affected by COVID-19, NAS has escalated its surge response to Level 3 which includes seeking support from external service providers.
"NAS are asking the public to help us help you by considering all care options available and only call 999 if it is an emergency."