We have heard it over and over again: The most important factor to re-opening society is widespread coronavirus testing.

South Korea’s cafes, for instance, were full last weekend after that country successfully launched a massive testing and contact tracing effort.

Widespread testing lets doctors see the virus from a bird’s eye view, where it is and where it’s not. That can allow people to come out of their homes, while ensuring those at risk remain in quarantine.

Despite the vital importance of testing, San Diego hospitals are massively underutilizing their full testing capacity. Local institutions have the capacity to complete at least 4,000 tests per day. And yet, during the last seven days only 1,125 tests were completed each day, on average.

That’s just a little more than 25 percent of full capacity.

In an official state of emergency – as San Diego is currently in – county public health officials are required to manage the local response. That means they provide guidance and even orders that local hospitals must follow.

Their most recent guidance instructed hospitals only to test the most ill people, or vulnerable patient groups, who are more likely to die from the virus. But such a limited testing strategy is not enough to begin to ease the lockdown – at least, not in a way that epidemiologists say would be safe. Hospitals need to test people with mild symptoms and even no symptoms to understand the prevalence of infection.

If hospitals are going to find a way to utilize their full testing capacity, it is local public health officials who must provide them with the blueprint.

When asked why testing is still so low, county officials and hospital officials gave differing explanations.

Dr. Eric McDonald, a county public health officer, suggested that a lack of personal protective equipment could be the cause. The county would like everyone with symptoms to be tested, said McDonald, but “the key is if we have enough protective equipment to protect those caregivers who are gonna get those tests from individuals.”

But several hospitals indicated that a lack of protective equipment has nothing to do with their unused capacity. They simply lack a wider testing strategy.

John Cihomsky, a spokesman for Sharp HealthCare, said Sharp’s hospitals are capable of doing 950 tests per day. But they are currently only completing an average of 300 per day, he said.

Sharp is already testing beyond the county’s guidelines. Doctors have begun testing cancer patients and pregnant women, and have the ability to request a test for anyone they believe should get one. Sharp has enough personal protective equipment to expand testing, Cihomsky said.

Likewise UC San Diego Health officials said they also have enough personal protective equipment to ramp up testing. UC San Diego Health has the ability to test up to 1,600 patients per day.

Dr. David Pride, an infectious disease specialist at UCSD, said they already expanded far beyond the county’s guidelines when it comes to testing. They’re testing everyone who comes into the hospital, he said.

But even testing everyone still leaves UCSD’s hospitals with lots of unused capacity.

After Voice of San Diego reported that testing had actually gone down in recent weeks, county officials announced they would create a task force to examine how to ramp up testing last Friday. That task force will meet for the first time next Monday, said Dr. Wilma Wooten, the county’s chief public health officer.

When asked why the county couldn’t ramp up testing immediately, Wooten said, “Rome wasn’t built in a day. … We’ve done a lot of work and will meet with our partners [including hospital representatives] for the next phase, next Monday.”

Wooten told the County Board of Supervisors, which oversees the public health department, on Tuesday that any expedited testing plan would include giving priority to vulnerable populations.

That could include older people in group homes and also certain racial groups who are more vulnerable to the virus, she said.

The task force will need to come up with a way for people to get to the tests. That could include health care workers going out into the community. Or it could mean certain groups are brought into hospitals or testing centers.

Representatives from Scripps Health, Sharp HealthCare and UCSD Health – three of the county’s largest hospital networks – told me they can complete 3,000 tests per day, combined. County public health officials have said they can complete another 1,000 tests per day at their laboratory.

County officials have also said several other institutions have additional capacity, which means the full testing capacity in San Diego could be well above 4,000.

A spokeswoman for Kaiser Permanente said the Kaiser hospitals of San Diego, Los Angeles, Orange, Riverside and San Bernardino Counties can run 2,500 tests per day, collectively.

McDonald, the public health officer, has said the county would need tens of thousands of tests per day to begin easing San Diego’s lockdown. Full testing capacity remains unclear. But it seems San Diego is much closer to a 10,000-per-day testing capacity than the 1,125-per-day average suggests.

Because USCD hospitals have begun testing everyone who comes in – including those who are asymptomatic – they are beginning to have a clearer picture of the infection rate. They are seeing roughly a 3 percent infection rate, said Pride.

That’s much lower than the county average as a whole, which is hovering around 7 percent, officials have said. The county average is much higher, because so far only those with the worst symptoms have been tested.

Pride said he thinks the infection rate needs to come down below 3 percent before San Diego can start easing its lockdown. But he also said it’s very important to get a better understanding of how prevalent the virus is through widespread testing.

“As we do more testing, we’ll have a good idea of prevalence. But we’ll have to get better at knowing who needs to be screened,” he said. “We have to get better at identifying cases, quarantining quickly and then doing contact tracing.”

The plan outlined by Pride is similar to what South Korean officials managed to quickly implement. Such a response locally would need to be coordinated by county public health officials.

State public health officials released guidance on Tuesday that hospitals should start widening the testing circle, according to the Los Angeles Times. Gov. Gavin Newsom has acknowledged the state has not done as well as it should in providing tests. California has done less than half as many tests as New York despite having a population more than twice its size, according to the Covid Tracking Project.

The response in the United States has been much more difficult to coordinate than in other countries, Pride pointed out.

“In the U.S. we don’t have a centralized health care system like other countries,” he said. “Unless you have a federal government that steps in and coordinates for you – the fact is it’s not being coordinated for us and that has added to the complexity and made it much more difficult.”

Correction: An earlier version of this post said Sharp HealthCare was following county guidelines for testing. A spokesman later clarified that Sharp is following its own internal guidelines.