Fig. 2From: Conceptual causal framework to assess the effect of SARS-CoV-2 variants on COVID-19 disease severity among hospitalized patientsBlocking non-causal associations between SARS-CoV-2 variants and COVID-19 disease severity among hospitalized patients by the use of a matched cohort design presented in a Directed Acyclic Graph (DAG). S = selection into the studyBack to article page