diff --git a/app/content/filters/registration.py b/app/content/filters/registration.py
index 3b58f83f..5e2819b4 100644
--- a/app/content/filters/registration.py
+++ b/app/content/filters/registration.py
@@ -36,4 +36,4 @@ def filter_year(self, queryset, name, value):
     def filter_has_allergy(self, queryset, name, value):
         if value:
             return queryset.exclude(user__allergy__isnull=True).exclude(user__allergy__exact='')
-        return queryset
+        return queryset.filter(user__allergy__isnull=True) | queryset.filter(user__allergy__exact='')
diff --git a/app/content/serializers/event.py b/app/content/serializers/event.py
index 8b9f26c2..f4ac7af9 100644
--- a/app/content/serializers/event.py
+++ b/app/content/serializers/event.py
@@ -263,6 +263,7 @@ class EventStatisticsSerializer(BaseModelSerializer):
     has_attended_count = serializers.SerializerMethodField()
     studyyears = serializers.SerializerMethodField()
     studies = serializers.SerializerMethodField()
+    has_allergy_count = serializers.SerializerMethodField()
 
     class Meta:
         model = Event
@@ -272,57 +273,14 @@ class Meta:
             "waiting_list_count",
             "studyyears",
             "studies",
+            "has_allergy_count",
         )
 
     def get_has_attended_count(self, obj, *args, **kwargs):
         return obj.registrations.filter(is_on_wait=False, has_attended=True).count()
-
-    def get_studyyears(self, obj, *args, **kwargs):
-        return filter(
-            lambda studyyear: studyyear["amount"] > 0,
-            map(
-                lambda group: {
-                    "studyyear": group.name,
-                    "amount": obj.registrations.filter(
-                        user__memberships__group=group, is_on_wait=False
-                    ).count(),
-                },
-                Group.objects.filter(type=GroupType.STUDYYEAR),
-            ),
-        )
-
-    def get_studies(self, obj, *args, **kwargs):
-        return filter(
-            lambda study: study["amount"] > 0,
-            map(
-                lambda group: {
-                    "study": group.name,
-                    "amount": obj.registrations.filter(
-                        user__memberships__group=group, is_on_wait=False
-                    ).count(),
-                },
-                Group.objects.filter(type=GroupType.STUDY),
-            ),
-        )
     
-
-class EventCategoriesSerializer(BaseModelSerializer):
-    has_attended_count = serializers.SerializerMethodField()
-    studyyears = serializers.SerializerMethodField()
-    studies = serializers.SerializerMethodField()
-
-    class Meta:
-        model = Event
-        fields = (
-            "has_attended_count",
-            "list_count",
-            "waiting_list_count",
-            "studyyears",
-            "studies",
-        )
-
-    def get_has_attended_count(self, obj, *args, **kwargs):
-        return obj.registrations.filter(is_on_wait=False, has_attended=True).count()
+    def get_has_allergy_count(self, obj, *args, **kwargs):
+        return obj.registrations.exclude(user__allergy__isnull=True).exclude(user__allergy__exact='').count()
 
     def get_studyyears(self, obj, *args, **kwargs):
         return filter(
@@ -352,47 +310,3 @@ def get_studies(self, obj, *args, **kwargs):
             ),
         )
     
-class EventRegistrationSerializer(BaseModelSerializer):
-    has_attended_count = serializers.SerializerMethodField()
-    studyyears = serializers.SerializerMethodField()
-    studies = serializers.SerializerMethodField()
-
-    class Meta:
-        model = Event
-        fields = (
-            "list_count",
-            "waiting_list_count",
-            "studyyears",
-            "studies",
-        )
-
-    def get_has_attended_count(self, obj, *args, **kwargs):
-        return obj.registrations.filter(is_on_wait=False, has_attended=True).all()
-
-    def get_studyyears(self, obj, *args, **kwargs):
-        return filter(
-            lambda studyyear: studyyear["amount"] > 0,
-            map(
-                lambda group: {
-                    "studyyear": group.name,
-                    "amount": obj.registrations.filter(
-                        user__memberships__group=group, is_on_wait=False
-                    ).count(),
-                },
-                Group.objects.filter(type=GroupType.STUDYYEAR),
-            ),
-        )
-
-    def get_studies(self, obj, *args, **kwargs):
-        return filter(
-            lambda study: study["amount"] > 0,
-            map(
-                lambda group: {
-                    "study": group.name,
-                    "amount": obj.registrations.filter(
-                        user__memberships__group=group, is_on_wait=False
-                    ).count(),
-                },
-                Group.objects.filter(type=GroupType.STUDY),
-            ),
-        )