COVID-19 collaborative screening: An action-research project for large scale contact tracing in Northern Portugal.

In late November 2020, when Europe reached the highest 14-day incidence of COVID-19 cases, the resource-intensive and time-consuming traditional contact tracing performed by Public Health was challenged. In this context, innovative approaches were necessary to guarantee a timely interruption of disease transmission. "COVID-19 Collaborative Screening" Project was developed as a faster solution, not only because the contact tracing process is simpler for the operator, but mainly because it is possible to quickly scale up the number of operators involved. It was designed to interrupt family and social transmission chains, in a partnership with the Local Public Health Services - allowing these services to dedicate to scenarios of more complex risk assessment, using the traditional contact tracing. To perform contact tracing, this method involves Public Servants, Armed Forces and Medical Dentists. The Project also promotes participatory citizenship, by delegating to the citizen the responsibility of registering his/hers contacts with high-risk exposure in an online form, in contrast to the traditional contact tracing method which is more health professional-dependent. Until the end of January 2021, the Project has trained eight teams, enrolling a total of 213 professionals, and was implemented in eight Health Regions (with an estimated population of 1,346,150 inhabitants). The Project was successful at facing the delays in case interview and contact tracing. The strategy implemented by ColabCOVID is assembled as a sustainable, reproducible and scalable platform and is ready to be re-implemented to face the emergence of more contagious variants, as well as an eventual forthcoming health threat.