## 3 COVID-19 and Tourism: Conceptualization  
The force field of COVID-19 is complex, as the combination of epidemiological spread patterns among groups or regions, time-varying vaccination programs (with different vaccines and different degrees of protection for specific social-medical groups), and different governmental intervention measures (e.g., mobility restrictions, lock-down measures) lead to dynamic and complex patterns. All these forces impact tourist choices and behaviors, e.g., destination choices, local destination mobility, and local visits to tourist amenities. The integrated assessment of COVID-19 impacts on spatial tourism patterns will be oriented towards an analysis of the above proposition on _'deconcentrated concentration'_ of tourism patterns. This latter concept will be explained in more detail now.  
Deconcentration is a term derived from industrial organization theory. It refers to a physical and managerial dispersion of functions and activities from a central corporate organization towards spatially and functionally separate divisions while maintaining a concentration of central competencies intact. This means that essentially a satellite network constellation is created, with a balance between spatial concentration ('hub') and functional deconcentration of activities. This regular business model is also replicated in the geography of spatial systems, where the concept of polycentricity has gained much popularity (see, e.g., [14; 15]). A polycentric system is a geographical configuration with a combination of centralized and decentralized functions, where agglomeration forces and spatial network linkages provide a hierarchical structure with functional spatial specialization.  
This polycentric conceptualization of spatial functions in terms of a major hub and complementary satellites will be used to describe the dispersion of tourism flows to Las Vegas during the COVID-19 pandemic. In this period, the awareness grew that a high concentration of tourists in a given tourist destination accompanied with a high density and close proximity of people is a potential threat to human health. To mitigate health risks in congested tourist concentrations such as Las Vegas, many visitors to Las Vegas were tempted to combine a visit to mass entertainment places with a healthy environmental trip outside, in particular trips to the Natural Parks outside the Las Vegas metropolitan area, even up to a daily distance of 300-450 miles. They might also combine a visit to several medium-sized environmental amenities with a trip to a major Natural Park destination (in a way similar to the 'intervening opportunities' idea advocated by [PERSON] [16]). This behavior in corona times was recently described as 'the path of least resistance' [17]. In the present study, tourists' spatial pattern of risk-avoiding mobility behavior in corona times will be called the 'Galaxy' system. The hypothetical spatial structure of this proposition is illustratively mapped out in Figure 1 in the form of a spatial 'Galaxy model.'  
Figure 1: A Galaxy structure of a ‘deconcentrated concentration’ in tourism.  
The literature on such emerging spatial 'Galaxy' constellations is sparse, but a few publications partly address these issues. Examples are found in the existing works of literature [18; 19] that studied the shift to small-scale and less mass-oriented tourist amenities. More generally, there is a noticeable shift to more sustainable and individualized forms of tourism [20] or outdoor activities [21].