Genetics, risk factors and COVID-19

How can we answer questions of causation ("what if?" questions) when we can't perform experiments directly? In the case of COVID-19, a typical causal question would look like this: what would happen if we prescribed people anti-inflammatory medications? Would it improve outcomes? While we can answer these questions definitively by performing a randomized trial, this approach is slow. With this outbreak, time is of the essence and there are many potential treatments to evaluate. Instead of performing the randomization ourselves, our approach is to exploit a randomization that nature has provided for us in genetics.