If the coronavirus outbreak in the U.S. gets really bad — if it stretches on longer than we anticipated, if huge numbers of people get sick, if the disruptions to daily life become even more severe — early flaws in the testing process will bear a lot of the blame.

The big picture: You probably know that there were some early problems with testing and that they’re getting better — which they are. But those early failures will help define the entire scope of this pandemic, and there’s not much we can do now to reverse the damage.

Why it matters: Because we haven't been doing enough testing, we don’t actually know how many people in the U.S. have the coronavirus. We know the official count is too low and that the number of confirmed cases is likely to explode in the coming weeks as testing improves.

But that's not the only problem. The lack of testing hasn't just left us in the dark about how bad the situation is; it has also made that situation worse.

By the numbers: Independent researchers estimate that the U.S. has completed about 20,000 coronavirus tests as of Friday.

By contrast, South Korea — a success story in controlling the coronavirus — has performed an estimated 250,000 tests.

As bad as that discrepancy is, it’s even worse when you consider that the U.S. population is more than six times bigger than South Korea's (327 million vs. 51 million).

Widespread, accurate testing has been a key component of other countries’ success in bringing their outbreaks under control.

When we can quickly and accurately diagnose one patient, we can immediately pinpoint who that person is most likely to have infected, then quarantine those people and test the ones who start to show symptoms, and repeat that process on down the line.

We can spot clusters of new cases, so that the public health system can react quickly and focus its resources.

But the U.S. has not been able to do those things on the scale we'd need. And so, experts say, the virus has probably been spreading undetected for weeks.

More people than we know about are infected, which means more people than we know about are spreading the virus, which likely means way more people than we know about are infected.

“Our response is much, much worse than almost any other country that's been affected," Ashish Jha, a public health expert and the director of Harvard’s Global Health Institute, told NPR last week.

"Without testing, you have no idea how extensive the infection is. You can't isolate people. You can't do anything," he said.

Between the lines: This makes other interventions, including individual “social distancing” and the cancellation of big events, even more important.

“We have to shut schools, events and everything down, because that's the only tool available to us until we get testing back up. It's been stunning to me how bad the federal response has been,” Jha told NPR.

What’s next: Testing capacity in the U.S. is improving quickly. Nationwide, we now have the ability to test about 26,000 people per day, according to former Food and Drug Administration commissioner Scott Gottlieb.

He expects that capacity to “rise substantially” this week.

As more people can get tested, we’ll be able to get a handle on how many cases there actually are, and to start focusing attention and resources appropriately.

How we got here: The testing shortfall has been a multiphase failure.

For reasons that remain unknown, the U.S. did not rely on the World Health Organization’s coronavirus test in the earliest days of the outbreak. Instead, the Centers for Disease Control and Prevention set out to make its own.

But the CDC’s test didn’t always work. Manufacturing had to be relocated following a possible contamination. And it has taken time to come up with a new one.

Regulatory red tape slowed down academic labs that wanted to jump in and develop their own tests, and capacity among private-sector labs is still ramping up.

In the early days, testing was focused narrowly on people who had traveled to China. And that was probably the best way to triage limited resources, but it was never going to be sufficient.

China and the U.S. are so thoroughly connected to the rest of the world that cases were always going to spread from China to multiple countries, and so travelers from multiple countries could bring it into the U.S. From there, people in the U.S. started spreading it themselves.

The bottom line: Yes, the testing capacity is about to catch up. When it does, we will see a tidal wave of new confirmed cases. The fact that we needed to catch up made that tidal wave bigger — made the outbreak worse. And that won't be undone by more tests now.