<http://ns.inria.fr/covid19/PMC7307645#title>	<http://purl.org/dc/terms/subject>	"Countries in Europe" .
<http://ns.inria.fr/covid19/PMC7307645#title>	<http://purl.org/dc/terms/subject>	"Northern European countries" .
<http://ns.inria.fr/covid19/PMC7307645#title>	<http://purl.org/dc/terms/subject>	"Ophthalmology" .