diff --git a/app/models/immunisation_import.rb b/app/models/immunisation_import.rb
index 6f085bb55e..cd0afa1d57 100644
--- a/app/models/immunisation_import.rb
+++ b/app/models/immunisation_import.rb
@@ -92,7 +92,7 @@ def parse_row(data)
   end
 
   def process_row(row)
-    patient = row.set_patient(candidates: @all_patients)
+    patient = row.set_patient(candidates: @patients_batch)
     vaccination_record = row.to_vaccination_record
 
     count_column_to_increment = count_column(vaccination_record)
@@ -100,7 +100,6 @@ def process_row(row)
 
     @vaccination_records_batch.add(vaccination_record)
     @patients_batch.add(patient)
-    @all_patients.add(patient)
 
     if (patient_location = row.to_patient_location)
       @patient_locations_batch.add(patient_location)
@@ -118,7 +117,6 @@ def process_import!
 
     @vaccination_records_batch = Set.new
     @patients_batch = Set.new
-    @all_patients = Set.new
     @patient_locations_batch = Set.new
     @archive_reasons_batch = Set.new
 
diff --git a/app/models/immunisation_import_row.rb b/app/models/immunisation_import_row.rb
index 2b38b2e3ab..92db1d9789 100644
--- a/app/models/immunisation_import_row.rb
+++ b/app/models/immunisation_import_row.rb
@@ -504,24 +504,23 @@ def existing_patients(candidates: nil)
       return
     end
 
-    if candidates.present?
-      # Match against the in-memory list of patients so far in this upload, before matching against the database
-      candidate_matches =
-        PatientMatcher.from_enumerable(
-          candidates,
-          nhs_number: patient_nhs_number_value,
-          given_name: patient_first_name.to_s,
-          family_name: patient_last_name.to_s,
-          date_of_birth: patient_date_of_birth.to_date,
-          address_postcode: patient_postcode&.to_postcode,
-          include_3_out_of_4_matches: false
-        )
+    database_matches =
+      PatientMatcher.from_relation(
+        Patient,
+        nhs_number: patient_nhs_number_value,
+        given_name: patient_first_name.to_s,
+        family_name: patient_last_name.to_s,
+        date_of_birth: patient_date_of_birth.to_date,
+        address_postcode: patient_postcode&.to_postcode,
+        include_3_out_of_4_matches: false
+      )
 
-      return candidate_matches if candidate_matches.present?
-    end
+    return database_matches if database_matches.present?
+
+    return if candidates.blank?
 
-    PatientMatcher.from_relation(
-      Patient,
+    PatientMatcher.from_enumerable(
+      candidates,
       nhs_number: patient_nhs_number_value,
       given_name: patient_first_name.to_s,
       family_name: patient_last_name.to_s,