In response to San Jose Inside’s prodding for more comprehensive testing data, Santa Clara County finally admitted how little it knows about the COVID-19 outbreak and how few people have been assessed for the highly contagious respiratory disease.

As of Sunday, the county Public Health Department lab has tested just 647 patients in a county of 1.9 million people, according to an FAQ posted online Monday evening.

In a phone call Sunday night, as we reported earlier today, county Executive Jeff Smith acknowledged that the actual number of infected people is probably somewhere closer to 4,000 or 5,000, although just 321 have tested positive to date.

How many tests private labs have conducted is something of a mystery since they have no obligation to report anything but positive results to local health officials. The county said the dearth of information and lack of widespread testing has hampered its ability to monitor the epidemic, mitigate its spread and inform people about their infection status.

“We appreciate you flagging the public’s questions regarding testing, and greatly appreciate your help and partnership with the county in sharing information with the public that will allow public health and the entire county organization to better protect and serve our community during this exceedingly challenging time,” county spokeswoman Betty Duong wrote in a letter to this news outlet before posting excerpts of it on the public health website. “Please reach out anytime if you are aware of issues you would suggest we prioritize as we do everything we can to share information around this quickly evolving and dynamic situation. We are doing our best but realize the demand for detailed information on everything that is happening is understandably insatiable.”

That said, she continued, while the county knows how many patients are tested in the public health lab, it has no clue how many are tested in other facilities. The problem is hardly unique to this county, which is grappling with a fractured system of public labs with fewer resource and stricter regulations and academic and commercial counterparts that report to federal authorities but not local governments.

“Large commercial laboratories have begun testing and have provided testing for patients of many different private and public healthcare delivery systems and test collection sites,” Duong wrote. “Some companies operate specimen collection sites but do not run their own tests; instead, they send those specimens to commercial labs for testing.”

Smith said on Sunday that an effort is underway to change that requirement. Duong reiterated as much in her letter tonight. “We are currently working on getting commercial labs to report all results to the Public Health Department,” she stated. “We are also working with the state and neighboring jurisdictions to obtain greater information about testing by private labs locally and regionally.”

According to the county, the public health lab performed its first COVID-19 test on Feb. 26, when the U.S. Centers for Disease Control (CDC) and Prevention finally authorized the diagnostic assays. Public health labs serve a limited role, county officials explained, by testing emerging infections such as COVID-19 while commercial and academic labs gear up to conduct high-volume analysis.

“For example,” the county FAQ explains, “at the beginning of the West Nile Virus epidemic, only public health laboratories were able to test for West Nile Virus, but West Nile Virus testing was very soon offered widely in the commercial sector. In the United States, unlike in some other countries, high volume testing is done exclusively by commercial private sector labs.”

The county public health lab can run a maximum of 100 tests a day, officials say, and only use kits from the CDC. The number of actual patients the lab can test is less than the volume of kits because some are used as controls and require multiple samples per person to ensure an accurate diagnosis.

“Our local public health laboratory, like all public health laboratories, functions as a specialty reference laboratory and as a bridge laboratory to enable testing to occur while other laboratory sectors come on-line,” the FAQ states. “The lab is not structured, physically and otherwise, to scale to commercial-volume testing. As a result, the current focus of the public health laboratory testing is to ensure that hospitalized patients get tested, as well as people who live or work in high risk settings such as long-term care facilities, healthcare professionals, and first responders, while we continue waiting for large-scale testing capacity to come on line through the commercial labs.”

There simply aren’t enough tests to go around.

“Unfortunately,” the county’s latest public health update reads, “local and national testing resources have not scaled to the extent that we expected, and not everyone who is ill can be tested at this time.”

Jennifer Wadsworth is the news editor for San Jose Inside and Metro Silicon Valley. Email tips to [email protected]. Follow her on Twitter at @jennwadsworth. Or, click here to sign up for text updates about what she’s working on.