The R0 is not an intrinsic feature of the virus. It can be lowered through containment, mitigation and ultimately “herd immunity,” as people who have recovered become less susceptible to infections or serious illnesses. For the epidemic to begin to end, the reproduction rate has to drop below 1. (The Washington Post)

This chart shows two curves with two very different virus reproduction rates. In the steepest curve, the virus reproduces quickly in a short period of time. In this scenario, emergency rooms, intensive care units and other parts of the health care system are overwhelmed. In an overwhelmed system, mortality rates can be high and those infected may not get the treatment they need. (World Economic Forum)

When the team modeled a scenario in which contacts were notified the instant a person tested positive, it was possible to push the reproductive rate of the virus below that threshold, the team reported in a preprint this week. (Science)