As a new wave of coronavirus cases hits the U.S. and Europe, governments are shifting away from total shutdowns toward more geographically targeted lockdowns to stifle the virus' spread.

Why it matters: Precision shutdowns can slow emerging outbreaks while lessening the overall economic impact of the response. But they risk a backlash from those who are targeted, and may not be strong enough to keep a highly contagious virus under control.

Driving the news: New York City tried to control a flare-up of new coronavirus cases this month by instituting partial shutdowns on a neighborhood-by-neighborhood basis, curtailing economic and social activity in areas harder hit by the virus while continuing reopening elsewhere.

• British Prime Minister Boris Johnson on Monday instituted a similar response for the U.K., putting in place a three-tier escalating system of lockdowns on a city or regional basis.
• "We don't want to go back to another national lockdown," Johnson told the British Parliament. But "we can't let the virus rip."

What's new: Some early research indicates more-targeted lockdowns can effectively smother outbreaks while leaving broader city and regional economies mostly intact.

• A paper published by a team of economists in July found a more precise shutdown focused on places where viral spread was most common could have reduced economic losses in New York by as much as 50% compared to a uniform lockdown.
• As long as new outbreaks are still in the relatively low flare-up stage, targeted lockdowns can efficiently cut off the oxygen to new spread. That seems to be the case in New York, where data released on Thursday indicates transmission has slowed in six of the ZIP codes that had been the focus of targeted lockdowns.

Yes, but: Individuals move around a city, and some epidemiologists worry that over time cases will break out of targeted lockdown areas and spark a wider outbreak.

• A preprint paper published in August found people were willing to travel outside of lockdown areas to get services they needed, potentially spreading the virus along the way.
• That was especially true for religious services. The paper found that during March, even as the total number of visits to churches declined, between 10% and 30% of churches nationwide saw increases in attendance. Those who were motivated to go simply went to churches outside of restricted areas.
• The small, seemingly geographically isolated outbreaks officials are focusing on may actually be the first signs that a city or region's control measures simply aren't working. As a result, “targeted measures can end up chasing the outbreak wider and wider, to the point where restrictions are equivalent to a broader blanket policy," epidemiologist Adam Kucharski told Wired.

What to watch: A targeted lockdown is inevitably going to appear to single out specific groups of people, which risks creating a backlash that can undermine public support for long-term control measures.

• That's already been the case in New York, where Orthodox Jewish communities have taken to the street to protest targeted lockdowns in their neighborhoods.
• In New York's Queens borough, stores and restaurants in one mall have been ordered closed, while those in an adjacent mall are still open, simply because of which side of the line they fall on.
• The experience of COVID-19 has already been a deeply unfair one, with both the direct health effects and indirect economic costs falling on those who can least afford it, and focused lockdowns will exacerbate that unfairness.

The bottom line: Targeted lockdowns can throttlethe virus while minimizing economic damage, at least in the short term. But one thing we've learned is that if COVID-19 gets out of control in one place, it may be only a matter of time before it ends up everywhere else.