diff --git a/cara/models.py b/cara/models.py
index 961ac6b7..041c208b 100644
--- a/cara/models.py
+++ b/cara/models.py
@@ -38,7 +38,7 @@ import typing
 import numpy as np
 from scipy.interpolate import interp1d
 import scipy.stats as sct
-from sklearn.neighbors import KernelDensity
+from sklearn.neighbors import KernelDensity # type: ignore
 
 
 if not typing.TYPE_CHECKING:
@@ -476,8 +476,9 @@ Virus.types = {
     ),
 }
 
-#@cached
-def _generate_virus_distribution(samples: int, qID: float=100) -> Virus:
+@cached
+def _generate_virus_distribution(params: typing.Tuple[int, float]) -> Virus:
+    samples , qID = params
     log_symptomatic_vl_frequencies = ((2.46032, 2.67431, 2.85434, 3.06155, 3.25856, 3.47256, 3.66957, 3.85979, 4.09927, 4.27081,
                                    4.47631, 4.66653, 4.87204, 5.10302, 5.27456, 5.46478, 5.6533, 5.88428, 6.07281, 6.30549,
                                    6.48552, 6.64856, 6.85407, 7.10373, 7.30075, 7.47229, 7.66081, 7.85782, 8.05653, 8.27053,
@@ -499,9 +500,9 @@ def _generate_virus_distribution(samples: int, qID: float=100) -> Virus:
     )
 
 Virus.distributions = {
-    'SARS_CoV_2': lambda n: _generate_virus_distribution(n, qID=100),
-    'SARS_CoV_2_B117': lambda n: _generate_virus_distribution(n, qID=60),
-    'SARS_CoV_2_P1': lambda n: _generate_virus_distribution(n, qID=100/2.25),
+    'SARS_CoV_2': lambda n: _generate_virus_distribution((n, 100)),
+    'SARS_CoV_2_B117': lambda n: _generate_virus_distribution((n, 60)),
+    'SARS_CoV_2_P1': lambda n: _generate_virus_distribution((n, 100/2.25)),
 }