diff --git a/cpp/models/ode_secir/parameters.h b/cpp/models/ode_secir/parameters.h
index 46708a943c..c276e0b9a7 100644
--- a/cpp/models/ode_secir/parameters.h
+++ b/cpp/models/ode_secir/parameters.h
@@ -245,7 +245,7 @@ struct MaxRiskOfInfectionFromSymptomatic {
     using Type = CustomIndexArray<UncertainValue<FP>, AgeGroup>;
     static Type get_default(AgeGroup size)
     {
-        return Type(size, 0.);
+        return Type(size, 1.);
     }
     static std::string name()
     {
diff --git a/cpp/models/ode_secirts/parameters.h b/cpp/models/ode_secirts/parameters.h
index 61052c0870..1ef4ea5dbf 100644
--- a/cpp/models/ode_secirts/parameters.h
+++ b/cpp/models/ode_secirts/parameters.h
@@ -429,7 +429,7 @@ struct MaxRiskOfInfectionFromSymptomatic {
     using Type = CustomIndexArray<UncertainValue<FP>, AgeGroup>;
     static Type get_default(AgeGroup size)
     {
-        return Type(size, 0.);
+        return Type(size, 1.);
     }
     static std::string name()
     {
diff --git a/cpp/models/ode_secirvvs/parameters.h b/cpp/models/ode_secirvvs/parameters.h
index bde271575f..a397be975a 100644
--- a/cpp/models/ode_secirvvs/parameters.h
+++ b/cpp/models/ode_secirvvs/parameters.h
@@ -357,7 +357,7 @@ struct MaxRiskOfInfectionFromSymptomatic {
     using Type = CustomIndexArray<UncertainValue<FP>, AgeGroup>;
     static Type get_default(AgeGroup size)
     {
-        return Type(size, 0.);
+        return Type(size, 1.);
     }
     static std::string name()
     {