**1. Introduction**

The increasing number of Major Incidents and Disasters (MIDs), either natural or man-made, necessitates preparedness in both human and material resources. This has become evident during the COVID 19 pandemic, which has caused tremendous pressure on Emergency Departments (EDs) in several countries. The concept of surge capacity initiated within the immediate period after an MID or the outbreak of a pandemic has the aim of increasing the number of staff and material, as well as creating spaces and structures based on validated and tested systems and procedures. However, an expanding incident necessitates an additional surge, a so-called secondary surge capacity with the intention of utilizing other possible resources. All these measures are implemented in accordance with the contingency plans for each organization, including healthcare, in order to create a more flexible surge capacity [1].

Most of the hospitals call in their sta ff and create operational spaces. The first stage entails sending home patients who are already admitted but do not need emergency care, or those who have already been treated and who can continue their recovery at home. This stage creates new beds and spaces for incoming patients. In the second phase, extra space should be created for the admission of emergency cases. Besides the ordinary ED, another admission unit is normally set up to handle either urgen<sup>t</sup> patients or ordinary, non-emergency cases. An outpatient department is usually used. Whilst adequate, this approach needs to be planned as there is a clear need for sta ff who are familiar with the locales, equipment that has to be adjusted to emergency requirements, and procedures that can be put in place as quickly as possible based on disaster medicine principles [2].

Previous studies have shown that sta ff who lack such familiarity can cause more harm than save lives, and unfavourable spaces can cause more challenges than facilitating the process. In particular, EDs should have sta ff qualified in emergency medicine, areas for triage and sorting, and proper devices for the care of the severely injured. The optimum suggestion is actually an existing unit that already handles emergency cases, i.e., a secondary ED [3–6].

The emergency department is one of the hospital's busiest facilities and is frequently described as a bottleneck that limits space and structures, jeopardising surge capacity [7,8]. In recent decades, overcrowding in emergency departments (EDs) has been reported as an increasingly worrying occurrence [9,10]. It has been associated with longer waiting times prior to treatment for severely ill patients, risk of in-hospital mortality and a higher probability of leaving the ED against medical advice or without being seen [11]. During the height of the COVID 19 epidemic in Europe and the US in spring 2020, EDs experienced a tremendous peak in the number of patient presentations. Preparedness for disasters became a significant concern in relation to health-care sustainability, and several city-based hospitals throughout the world were operating at or near to capacity limits [12].

The issue of everyday overcrowding of EDs and the impact on preparedness to handle peaks such as that during COVID 19 appeared to be complex, with several factors including physical distancing, use of personal protective equipment and hygienic measures needing to be considered along with remedies required [13].

In the early 1980s, an increasing number of emergency cases led to the establishment of Urgent Care Centres (UCCs) [14]. They function as a healthcare provider sta ffed by primary care physicians, registered nurses and nurse practitioners, with the ability to handle emergency conditions that do not need ED amenities. UCCs are often managed by a hosting hospital and share mutual support systems such as laboratory, radiation and medical services. It has been reported that UCCs reduce the overuse of EDs by up to 48% [15]. Doran showed that patients treated by UCCs, sited together with and in close collaboration with an ED, received swift service and better follow-up than the control group in the study [16]. UCCs and EDs have also proven to be horizontally integrated and collaborative and function informally between ED and UCC sta ff [17].

This paper suggests that UCCs may be suitable units for beneficial use both in peacetime and during an MID. They fulfil the function as a supportive unit in peacetime, and by using the same sta ff and resources can easily be converted to an extra ED or a pandemic admission unit as evidenced by the current need during the COVID 19 epidemic. With the first UCC having been set up in Sweden, the aim of this study was to investigate the outcome of treatment in the ED versus the UCC in terms of quality, LOS, time to physician (TTP), use of medical services, referrals, revisits, hospitalisation, mortality and costs. If it was the case that these parameters were equal to the ED, the UCC could be used as a complementary unit to the ED, improving sustainability not only in peacetime but also during MIDs.
