Beyond the blame game: Unraveling the complex relationship between density and COVID-19 through a systematic literature review

Density has gained considerable attention in policy and scientific discourses since the emergence of COVID-19. In the early days, density was blamed as a negative factor that accelerates the transmission of coronavirus in urban areas. Following this, many studies have examined the impact of density on the spread of COVID-19. This offers a good opportunity to examine and synthesize the insights reported in the literature to understand how density affected the spread of the virus. To do so, we have conducted a systematic literature review of 134 papers, which around 58 % of them found density as a positive predictor. However, we found that the relationship between density and the spread of the virus is complex and mediated by factors such as scale, context, methods used for analysis, and other built environment factors. Hence, we assert that the relationship between density and infection rate is not straightforward, and assertions about the effects of density on COVID-19 transmission can only be made with caution. Comprehensive analyses taking into account multiple complex and interrelated factors need to be carried out before any conclusions regarding this issue can be drawn. Therefore, it is advisable to refrain from making premature statements due to their potential adverse effects on efforts toward the development of cities that are resilient to climate change and contribute to achieving sustainable development goals.