The US is finally starting to take its response to the coronavirus pandemic seriously.

To slow the spread of the disease, more of the US should follow New York City's lead and go under lockdown.

This means closing schools, restaurants, and bars as well as limiting travel and working from home.

This decision is drastic and painful, but it will save lives.

This is an opinion column. The thoughts expressed are those of the author.

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After wasting weeks underestimating the threat of the novel coronavirus, the US is finally taking meaningful action to slow its spread.

Unfortunately, we are still behind where we need to be.

The next big step is "lockdown." New York City, Los Angeles, Massachusetts, Ohio, and other cities and states have started taking this brave and painful step. The rest of the country should prepare to do it soon.

The data is clear. Locking down to slow the spread of the coronavirus helps "flatten the curve," reducing the infection rate and, thereby, reducing the impact on local healthcare systems. The short-term economic and social impact is devastating, But once we get a handle on the epidemic, the economy will recover.

China, South Korea, Italy, Spain, France, Denmark, and other countries have already gone to some form of lockdown. More of the US should follow their lead. Every day we wait will mean thousands more Americans getting sick and needing medical attention, potentially overwhelming local healthcare systems.

New research on the Italy outbreak shows the impact of shutting down fast. The coronavirus in Italy was first identified in a province called Lodi, which shut down February 23 (green in the chart below). Another province, Bergamo, started with fewer cases but did not shut down until March 8. The number of cases in Bergamo has since far exceeded the number in Lodi (University of Oxford & Nuffield College, UK).

Shutting down early slows the spread of the coronavirus and "flattens the curve." University of Oxford & Nuffield College, UK

The rate of coronavirus infection in the US is closely tracking that in other countries. Because of the lag between infection and serious symptoms — and the ongoing lack of sufficient US testing capacity — the virus has already probably spread more widely in the US than most people realize. The number of identified cases is growing at a rate of about 33% a day. Every three days we wait, therefore, will mean twice as many Americans getting infected.

Lockdowns won't stop the spread of the virus, but they will slow it. For a graphical explanation of how and why, read and watch this brilliant illustration from The Washington Post.

Three weeks ago, Italy had three confirmed coronavirus cases. Eleven days ago, it had about 2,500 — roughly the number of confirmed cases in the US on Saturday. After weeks of local social-distancing measures, the whole of Italy went into lockdown last Tuesday.

We are about 11 days behind Italy. Acting now will almost certainly save lives. It will reduce the spread of infections while our testing capacity ramps up and our healthcare providers do what they can to prepare for an onslaught of critical cases. It will flatten the curve and reduce future pressure on our healthcare system.

Samantha Lee/Business Insider

What does "lockdown" mean?

Closing schools

Closing restaurants (except takeout), bars, movie theaters, and other establishments where people gather

Stopping nonessential travel

Working from home wherever possible

Staying home except for essential work and food trips and "socially distanced" fresh air (for example, walking dogs or exercising a safe distance from other people)

Italy waited to go to full lockdown, and it is now paying the price. In areas like Bergamo, there are not enough beds and ventilators to treat everyone who needs intensive care. So doctors are having to triage — deciding who to treat and who to let die.

Another reason to take this step is that early evidence suggests that even those without symptoms are spreading the coronavirus. The lack of testing capacity in the US means we are not yet testing even all those who have symptoms, let alone people who may have been exposed. So our testing thus far most likely provides a far too optimistic picture of how far the virus has spread.

Sunday morning on "Meet the Press," one of the nation's top epidemic experts, Dr. Anthony Fauci, suggested that the US should finally be proactive rather than reactive — "be overaggressive and get criticized for overreacting." In short, better safer than sorrier. If the threat turns out to be less serious than it now appears to be — if increased testing tells us that the virus is not as widespread as feared — we can dial back.

Yes, more shutdowns will have huge social and economic consequences. They will require massive government aid to tens of millions of Americans and businesses. But they will also slow the rate of infection, spread out the impact on our healthcare system, and reduce the anguish of not being able to help family members, colleagues, and friends who could be saved.

Based on everything we know, we're headed for lockdown anyway.

The sooner the better.