define "Adverse Events for Immunization":
  [AdverseEvent] AE
    where AE.actuality = 'actual'

/*
@numerator: Number of AEFI cases during the reporting period
@pseudocode: COUNT of immunization events WHERE "Reaction reported" is "Yes" AND "Date and time of vaccination" is during the reporting period
*/
define "Numerator":
  exists Elements."Adverse Events for Immunization"

define "Stratification 4":
  Elements.GetGeographicRegionForImmunization( Immunization )

define "Stratification 3":
  First( First (Elements."Adverse Events for Immunization" ).seriousness.coding )

define "Stratification 2":
  Immunization.manufacturer

/*
@disaggregation: Vaccine type: BCG, OPV, etc.
                 Vaccine manufacturer
                 Type of reaction: non-serious, disability, etc.
                 Administrative area
                 Reaction manifestation: rash, vomiting, etc.
*/
define "Stratification 1":
  First( Immunization.vaccineCode.coding )

/*
@denominator: Not applicable
@pseudocode: Not applicable
*/
define "Denominator":
  true

/*
 * As defined by Member State
 */
define "Initial Population":
  true

define function ToString(value AdverseEventActuality): value.value

/** 
 * @function
 * @param immunization The immunization record for which the location should be retrieved
 * @return FHIR.address The location that the immunization event occurred
 */
define function GetGeographicRegionForImmunization(immunization Immunization):
  (
    [Location] L
        where immunization.location.references(L)
  ).only().address.state

define fluent function only(locations List<Location>):
  singleton from locations

/*
@description: Returns true if the given reference is to the given resource
@comment: Returns true if the `id` element of the given resource exactly equals the tail of the given reference.
NOTE: This function assumes resources from the same source server.
*/
define fluent function references(reference FHIR.Reference, resource FHIR.Resource):
  resource.id = Last(Split(reference.reference, '/'))

define function ToString(value string): value.value