The U.S. West Coast is offering hopeful signs that early social distancing efforts worked, allowing officials to increase hospital capacity and slowing the spread of the novel coronavirus.

In California, the situation is unstable and state officials fear a sudden increase in patients. Yet distancing measures may help ease a potentially crushing burden on medical institutions, California Governor Gavin Newsom said.

“The stay-at-home order has advanced our efforts in reducing the stress on the system,” Newsom said in a briefing Monday. “It’s bought us time to prepare.”

His optimism is muted, in part, because the latest case numbers may also reflect Covid-19 testing challenges, including delays in returning results, which are widespread but particularly pronounced in California. Roughly 84,000 tests had been conducted in California as of Saturday, nearly 70% of which have results pending, according to the state health department.

Still, in Washington state, additional signs suggest the curve of case growth is flattening in the initial epicenter of the U.S. outbreak. Last week, Governor Jay Inslee reported a small decrease in the pace, largely due to improvements in King County, which includes Seattle, and two others nearby.

As of March 18, each King County patient was transmitting Covid-19 to 1.4 other people on average, down from 2.7 at the beginning of March, according to Daniel Klein, a senior research manager at the Institute for Disease Modeling in Bellevue. The reductions show up in numbers collected by hospitals, too.

The Washington State Hospital Association’s data for King and Snohomish counties also show “the curve is flattening over the last few days,” said Janet Baseman, associate dean for public health practice at the University of Washington School of Public Health. “It’s not accelerating, so that’s great. We’re just not out of the woods.”

The Washington hospital chain that in January treated the first known U.S. patient is seeing a similar trend.

“There’s at least a glimmer of hope,” said Rod Hochman, chief executive officer of Providence St. Joseph Health, which operates in seven Western states. “We’ve been at this for two months. Northwesterners have been working from home. We’ve been doing a lot of social distancing for a while.”

The goal of such measures is to spread the load of illness over a longer period -- flattening the curve, as the now-common term goes. When cases are plotted out over time, officials want them to resemble a long and imposing hill, but one with a gentle incline. They want to avoid a dramatic alpine peak that will overtax hospitals.

Microsoft, based in the Seattle suburb of Redmond, on March 4 asked employees to work from home. Shortly after, Amazon did the same for its Seattle-area office workers. Washington public schools have been closed since March 16, and some private ones shut a week before that.

That said, Washington implemented a formal stay-at-home order only last week and the virus spread among workers at some companies that remained open. As of last weekend, 54 Boeing workers in the Puget Sound were sick.

In Oregon, where Governor Kate Brown declared an emergency March 8 and canceled school March 16, the rate of increase has been relatively flat. In the 10 days since Oregon topped 100 confirmed patients, cases have risen to 606. At the same point in its outbreak, Florida had triple that, New York more than quadruple and Michigan more than 7½ times, according to data compiled by the University of Chicago.

There’s further evidence for the efficacy of distance measures in Ohio, where Mike DeWine was among the first U.S. governors to close schools, bars and restaurants. He even supported closing the polls for the state’s March 17 primary after a court refused to.

Before Ohio had reported its first confirmed case, DeWine announced March 3 that Ohio would bar general spectators at the Arnold Sports Festival with Arnold Schwarzenegger in Columbus, an event that draws thousands from many countries. DeWine said he agonized, but now the decision seems like “a no-brainer.”

State officials caution that the virus likely is more widespread than reporting suggests because of limited testing -- and that Ohio could see as many as 10,000 new cases a day at the peak of the outbreak. But the state had 1,933 and 39 deaths as of Monday, fewer than neighboring Pennsylvania and Michigan.

Detroit, with a large population of poor citizens, has been a particularly hot zone. New Orleans, Chicago and Phoenix all are predicted to be especially virulent as well. And even within states that acted early, similarly afflicted areas may still emerge.

One example is California, the nation’s most populous state, with its diverse populations and geographies. Providence’s Hochman, who operates hospitals in northern California, Los Angeles and suburban Orange County, says it’s “six different states rolled into one.”

Even just within Los Angeles, downtown may face case intensity similar to New York City’s because of its density, he said. There’s not enough data to be sure.

San Francisco’s top public health official, Grant Colfax, said it’s too soon to know whether early and aggressive social distancing orders made a difference. “I certainly am hoping and praying that that is the case,” he said.

The city has 374 confirmed cases and six deaths. And there’s a growing outbreak in Laguna Honda Hospital, a long-term-care facility where nine staff and two residents have tested positive.

Six Bay Area counties on March 16 were the country’s first to issue stay-in-place orders. Soon after, Newsom made the shutdown statewide.

“We’re early into this, but we are seeing evidence that the epidemic curve elsewhere is steeper,” said Matt Willis, public health officer for Marin County.

Yet Los Angeles is close to New York-level spread, Mayor Eric Garcetti and Newsom said at a news conference Friday; the city could have as many cases per capita as early as this week. A Navy medical ship arrived in Los Angeles on Friday to provide extra hospital beds.

Even in towns with a flatter curve, “You’re not saying there are going to be fewer hospitalized people. You’re saying they’re going to occur over a longer period of time,” said Bela Matyas, public health officer in Solano County, in the Bay Area.

Distancing requires time to bring the disease to heel. Coronavirus can take nearly a week after transmission to yield symptoms and another week or two after that for the sickest patients to end up in intensive-care units, said Jeff Duchin, Seattle and King County health commissioner.

“What we are looking at today reflects infections that happened several weeks ago,” he said. “If we want to know how well we are doing today, it takes two to three weeks for those infections to mature into illnesses, hospitalizations and deaths.”

Still, there’s hope the initial progress will point the way for other states and cities.

“The next week or so will tell us an awful lot,” Providence’s Hochman said. “Depending on how this all turns out, one of the take-home messages is that the social distancing and the work the three governors in Washington, Oregon and Cailfornia did is actually going to make a difference. A lot of folks said they were overreacting. But they got on it early.”

Any gains, though, are hard-won and precarious, said Duchin.

“It looks like we are going in the right direction, but we don’t have a lot of certainty,” he said. “And if it’s true, it means we need to continue what we are doing, because if we stop, the epidemic will come roaring back.”

--With assistance from David R. Baker, Mark Niquette and Emma Court.

This article was provided by Bloomberg News.