The article describes the risks for the mental health and wellbeing of urban-dwellers in relation to changes in the spatial structure of a city that could be caused by the COVID-19 pandemic. A year of lockdown has changed the way of life in the city and negated its principal function as a place of various meetings and social interactions. The danger of long-term isolation and being cut-off from an urban lifestyle is not only a challenge facing individuals, but it also creates threats on various collective levels. Hindered interpersonal relations, stress, and the fear of another person lower the quality of life and may contribute to the development of mental diseases. Out of fear against coronavirus, part of the society has sought safety by moving out of the densely populated city centres. The dangerous results of these phenomena are shown by research based on the newest literature regarding the influence of COVID-19 and the lockdown on mental health, urban planning, and the long-term spatial effects of the pandemic such as the urban sprawl. The breakdown of the spatial structure, the loosening of the urban tissue, and urban sprawl are going to increase anthropopressure, inhibit access to mental health treatment, and will even further contribute to the isolation of part of the society. In addition, research has shown that urban structure loosening as a kind of distancing is not an effective method in the fight against the SARS-COV pandemic. Creating dense and effective cities through the appropriate management of development during and after the pandemic may be a key element that will facilitate the prevention of mental health deterioration and wellbeing. It is also the only possibility to achieve the selected Sustainable Development Goals, which as of today are under threat.