A lower bound for the order parameter in the one-dimensional contact process

It is shown that ϱ(λ) ≥ (1 − λc/λ)(2λ2 + 3λ + 2)((λ2 + λ)(1 + λc)), where λc is the critical value and ϱ(λ) is the order of the one-dimensional contact process with parameter λ. An implication of this inequality for vaccination policies for epidemic diseases is discussed.