Many people suggest that "Vaccines kill" and use (often spurious) data to suggest that vaccines are dangerous. While an association may exist, that does not mean that a logical (or causal) link necessarily exists between vaccines and death. Counterfactual thinking can serve as a way to clarify this association. In the model given in the Book of Why, we see that 99 children (out of 1 million) die from the vaccination. Meanwhile, a counterfactual world in which there is no vaccination leads to 3,861 deaths. In other words, deaths are present in both scenarios, but there are many more deaths in the non-vaccine scenario, thus supporting the efficacy of vaccination.