As Santa Clara County residents enter a fourth week under orders to stay home to reduce the spread of the coronavirus, county public health officials concede that there has been little progress rolling out large-scale testing to see just how far the virus has proliferated.

In a well-attended virtual town hall meeting Sunday, Santa Clara County Public Health Officer Sara Cody said the testing capacity for COVID-19, the illness caused by coronavirus, is behind where she expected it to be by early April, making it difficult to test more than a small slice of the county population exhibiting clear symptoms.

The hope was that, by working with the commercial sector, there would be widespread testing available at this point, Cody said.

"To be perfectly blunt, that is not the case," she said. "To date, less than 10,000 patients in our county have been tested."

Santa Clara County's population exceeds 1.9 million.

Media reports have surfaced in recent days detailing the slow testing speeds of private labs serving states including California, which has fallen behind other states in the rate of testing per capita. Cody said there are reasons limiting the ability of commercial labs from scaling up — some known to her, and some unknown — but the result is that the county must prioritize testing for those who are symptomatic.

"It is very challenging, but at this point we do not have the testing capacity that we need," she said. "We've tried to have an impact on the parts of the system that are within our control, but unfortunately much of it is not in our control."

The comments came after a county resident inquired about his ability to safely check on his 98-year-old mother. He is asymptomatic, but could still be a carrier of the virus and put vulnerable residents at risk, yet he would not be able to get tested for COVID-19. The total number of confirmed cases in Santa Clara County now exceeds 1,200 — higher than neighboring counties yet likely only a fraction of the true infection rate.

Congresswoman Anna Eshoo, D-Palo Alto, laid much of the blame on a late start by the Trump administration and the Centers for Disease Control and Prevention. Stemming an outbreak means isolating those who are infected, she said at the meeting, which means you have to have an accurate test that can be quickly and effectively deployed.

Instead, she said the federal department released a faulty test that eventually had to be recalled due to errors that included false positives. The country lost four important weeks of diagnostic testing, she said, and on the heels of that "debacle," the Trump administration put a call out to the private sector to ramp up testing.

"We've been playing catch-up ever since, and we lost such highly valuable time because the virus continued to spread," Eshoo said.

More recently, Stanford researchers last week began testing a large cross-section of county residents for antibodies that can confirm whether or not someone has contracted COVID-19. Cody said the test has been conducted across all of the geographic areas of the county, and should give public health officials a better idea of how much of the county population may have been affected by the virus to date. It could also shine a light on how long the coronavirus has been circulating in the county undetected, and how many people have built up an immunity.

It's still "some time off" before people in the county will be able to get tested for antibodies and learn about their own status, Cody said.

Dr. Yvonne Maldonado, Stanford's chief of infection control, said during the call that university researchers had only received approval from the U.S. Food and Drug Administration for its test on Friday, and will be conducting "limited tests" this week and figuring out how to interpret the results. It's not clear at this point, Maldonado said, whether the presence of antibodies prevents reinfection, or whether the antibodies can kill the virus in an experimental lab setting.

First in line to get the test will likely be health care workers, ensuring it is safe for them to work with patients without putting them at risk, she said.

The bright spot during the town hall meeting was that Santa Clara County's shelter-in-place order may be working. Since the local prohibition on mass gatherings and the closure of nonessential businesses, Cody said the virus appears to be spreading more slowly relative to other areas, despite being ground zero for the virus in prior months.

"I would say that I am cautiously optimistic that the early action we took here in the Bay Area and the extreme measures we have in place will help us avoid a worst-case scenario," Cody said.

From the county's perspective, the worst-case scenario has always been a surge of COVID-19 patients with acute symptoms flooding local hospitals, overwhelming the available beds, ventilators and staffing needed to keep them alive. County data shows that about half of the roughly 1,500 acute hospital beds are in use, 175 of which are COVID-19 patients as of Sunday.

Dr. Mark Adams, chief medical officer for El Camino Hospital, said the hospital has cut back on elective surgeries and procedures to provide extra capacity, and is closely monitoring the number of ventilators and negative pressure rooms designed to prevent infection.

"We've maintained plenty of capacity," he said. "At least for us, now that's not a concern."

Staying home and taking protective measures dulls the feared spike in patients requiring hospitalization — hence the phrase, "flattening the curve" — but does mean the virus will likely linger longer as a result, Adams said.

The town hall meeting, hosted by Santa Clara County Supervisor Joe Simitian over the phone, drew massive participation from the public. At its peak, the Sunday morning meeting had 8,000 participants.

When polled, 54% of people listening in on the call felt that the ability of hospitals and health care systems to keep up with acute cases was their highest concern. Worries about at-risk and elderly patients trailed at a distant second with 21%, followed by loss of jobs and the economy at 20%. Only 5% of respondents felt school closures and lost educational opportunities was their top concern.

Two additional town hall meetings have been scheduled for April 26 and May 17.

Find comprehensive coverage on the Midpeninsula's response to the new coronavirus by Palo Alto Online, the Mountain View Voice and the Almanac here.