This code system http://terminology.hl7.org/CodeSystem/adverse-event-seriousness defines the following codes:

CodeDisplayDefinition
non-serious Non-seriousThis event is considered not to have the potential for persistent or costly injury or consequence.
serious SeriousThis event is considered to have the potential for persistent or costly injury or consequence.
 <status value="draft"/> <experimental value="false"/> <date value="2020-04-09T21:10:28+00:00"/> <publisher value="HL7 (FHIR Project)"/> <contact> <telecom> <system value="url"/> <value value="http://hl7.org/fhir"/> </telecom> <telecom> <system value="email"/> <value value="fhir@lists.hl7.org"/> </telecom> </contact> <description value="Overall seriousness of this event for the patient."/> <caseSensitive value="true"/> <valueSet value="http://terminology.hl7.org/ValueSet/adverse-event-seriousness"/> <content value="complete"/> <concept> <code value="non-serious"/> <display value="Non-serious"/> <definition value="This event is considered not to have the potential for persistent or costly injury or consequence."/> </concept> <concept> <code value="serious"/> <display value="Serious"/> <definition value="This event is considered to have the potential for persistent or costly injury or consequence."/> </concept> </CodeSystem>