Population differences in completeness and reliability of Dutch COVID-19 registry data: The influence of testing policy, test readiness, and registration policy from an epidemiological perspective.

During the COVID-19 pandemic, the bidirectional relationship between policy and data reliability has been a challenge for researchers of the local municipal health services. Policy decisions on population specific test locations and selective registration of negative test results led to population differences in data quality. This hampered the calculation of reliable population specific infection rates needed to develop proper data driven public health policy.