“Whenever you see the virus, it’s moved on already — it will have infected other people by the time you become aware of it,” said Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health. “Slowing it down matters because it prevents the health service becoming overburdened. We have a limited number of beds; we have a limited number of ventilators; we have a limited number of all the things that are part of supportive care that the most severely affected people will require.”

In a country whose government is unlikely, or unable, to impose draconian limits on freedom of movement as China did, such voluntary measures may be the best countermeasure. The reason isn’t that it will stop the virus; it’s likely the same number of people will ultimately still get sick. But it could mean the difference between a manageable surge of patients and one that overwhelms scarce resources, resulting in unnecessary deaths.

Social distancing won’t just require government-level decisions — individual people will need to take steps to change their daily routines, based on their own judgment and the local situation. By the time it stops feeling silly to consider major life changes, it may be too late.