Earlier is better.

In a fast-moving pandemic like Covid-19, when there is no cure, no vaccine, time is the key to saving lives.

To put it another way: the sooner you take action, the fewer people will die.

That’s the conclusion of two British epidemiologists who wrote an opinion piece for the New York Times. The numbers they cite are stunning.

Britta and Nicholas Jewell estimate that “90 percent of the cumulative deaths in the United States from Covid-19 … might have been prevented by putting social distancing policies into effect two weeks earlier [than they were], on March 2, when there were only 11 deaths” in the entire U.S.

Starting even one week earlier, on March 9, they say, could have reduced deaths by 60 percent.

Whatever the final death toll is in the United States, the cost of waiting will be enormous, a tragic consequence of the exponential spread of the virus early in the epidemic,” the Jewells say.

They focus on what happened in New York state, and especially New York City, where a revised calculation now shows that more than 10,000 people have died from Covid-19. That number now includes people who succumbed before being tested.

The order to stay at home and to employ social distancing and other efforts to blunt the coronavirus attack was not issued in New York state until March 22.

“The point here is not to cast blame on mayors or governors for the timing of what were difficult decisions for both public health and the economy, but rather, to alert cities and states where full social distancing measures are not in place that hesitation can come at a very high cost,” the Jewells write.

It’s always too late if you wait until you think the number of deaths is sufficient to act.”

To bolster their argument, the Jewells cite the experiences of neighboring states Kentucky, which ordered social distancing on March 26, and Tennessee, which did so just five days later:

“As Kentucky moved to full statewide measures in reducing infection growth, Tennessee was usually less than a week behind. But as of Friday, the result was stark: Kentucky had 1,693 confirmed cases (379 per million population); Tennessee had 4,862 (712 per million).”

The writers emphasize that while “lockdowns are not a solution to the virus … they do buy us time to better prepare for further waves of infection and to develop treatments and vaccines.”

And they underline the next round of critical timing decisions: when to begin easing the restrictions.

“Getting that wrong will lead to second wave of infections and a return to lockdowns,” they say. “We can’t afford to repeat the same mistakes.”