Chasing the ghost of infection past: identifying thresholds of change during the COVID-19 infection in Spain

Luis Santamaria; Joaquin Hortal

The spread and growth intensity of the COVID-19 pandemic is being driven by international connectivity (Coelho et al. 2020) , which resulted in repeated exposition of the highly interconnected European population. In the case of Spain, this has been particularly important at international hubs such as Madrid or Barcelona, although contagions due to tourism and sport events also initiated the spread at least in Málaga and Valencia (southern and eastern coasts, respectively), spreading the disease and facilitating community transmission throughout the whole Spanish territory (see Table S1 ). This implies that the risk of new introductions from abroad will regain importance, should the objective of flattening the curve and taming the outbreak succeed in Spain. Our results, however, underscore the importance of the prolonged delays between infection and detection for the early (re)containment of the infection. Though population awareness and widespread adoption of preventive measures will likely slow down the advance of the disease in the future, this does not diminish the importance of implementing a much more active and complete system of early detection. This represents a formidable challenge for Spain, whose public health and R&D systems (the latter being instrumental for supporting testing efforts) were severely affected by the post-2008 austerity measures.