  Motivated by the global unrest related to the COVID-19 pandemic, we present a
system prototype for ontology-based, integration of national data published
from various countries. COVID-related data is published from different
authorities, in different formats, at varying spatio-temporal granularity, and
irregularly. Consequently, this hinders the joint data exploration and
exploitation, which could lead scientists to acquire important insights,
without having to deal with the cumbersome task of data acquisition and
integration. Motivated by this shortcoming, we propose an approach for data
acquisition, ontology-based data representation, and data transformation to
RDF, which also enables interlinking with other publicly available data
sources. Currently, data coming from the following European countries has been
successfully integrated: Austria, Belgium, France, Germany, Greece, Italy, and
Sweden. The knowledge base is automatically being updated, and it is available
to the public through a SPARQL endpoint and a direct download link.
Furthermore, we showcase how data integration enables spatio-temporal data
analysis and knowledge discovery, by means of meaningful queries that would not
be feasible to process otherwise.
