http://purl.org/vodan/whocovid19crfsemdatamodel/Skin_ulcers
http://purl.obolibrary.org/obo/NCIT_C54247
http://purl.org/vodan/whocovid19crfsemdatamodel/signs_and_symptoms
http://purl.org/vodan/whocovid19crfsemdatamodel/YNU_Question