As some rushed to grab a quick, $47 blood test from a doctor in Little Saigon that can detect antibodies to the novel coronavirus in just minutes, the Orange County Health Care Agency issued a stern warning against them this week.

“These non-approved tests can produce false results and lead to unintended negative consequences for the individual and the broader community,” Orange County Health Officer Nichole Quick said in a statement.

A false negative could lead someone who actually has COVID-19 to believe they’re fine and circulate confidently in the community, unaware they may actually be spreading the virus.

Currently, no FDA-approved serology, or blood, tests for COVID-19 are available in the United States, Quick said.

The Southern California News Group reported on the unorthodox protocol on Wednesday. Contacted at that time, the Orange County Health Care Agency declined comment and referred questions to the Orange County District Attorney’s Office.

A district attorney’s investigator spoke to the doctor, Michael Dao, and determined he had not made any false claims about the serology tests.

There are two main types of tests for the coronavirus.

The most accurate, FDA-approved test is a molecular type that identifies the virus’ DNA via swabs of a patient’s nose or throat, OCHCA said. The polymerase chain reaction, or PCR, testing is the type used by the Public Health Laboratory and commercial labs reporting to the HCA. It’s also in terrifically short supply.

Blood test detects antibodies

The other is a serology test, which examines the blood for antibodies to the virus. This type of test is used by public health officials to measure how widely a virus has actually spread — antibodies remain in the blood long after the virus is gone — but it’s frowned upon for individual diagnoses of the disease.

It’s that latter test, of antibodies in the blood, that Dao has imported from South Korea and is using. Officials say that could be dangerous.

“We want to ensure our community members are getting accurate information about their health, and accurate information drives appropriate medical care,” Quick said.

People should understand that there’s no guidance from the U.S. Centers for Disease Control and Prevention on how to interpret or take public health action in response to a positive or negative COVID-19 serology result, that any company claiming FDA approval or authorization for a serology test is misleading the public, and that no COVID-19 serology test kits have been reviewed by the FDA or have received Emergency Use Authorization, she said.

“We do not have parameters to interpret those results,” she said.

200 tests so far

Over the past two weeks, Dao, a 55-year old internist who operates the Dao Medical Group in Orange County’s Little Saigon, has administered some 200 COVID-19 IgG/IgM Rapid Gold tests provided by PCL Inc., one of the largest biotech firms in South Korea.

He was awaiting delivery of 12,000 more.

“No test is perfect,” Dao said by email. “If a person gets exposed to the virus recently in the past few days, the antibodies may not develop, so it may show negative, but that is why we don’t encourage people with acute, severe disease to use this serology test.

“This is a good tool for people with no or mild symptoms, people who don’t know that they are infected and still working or going around and getting other people infected. This serology test can be performed easily and less risk to the healthcare providers, can be done mass testing with ease. This test is much more simple than the PCR, using nasopharyngeal swab specimen we are currently using.”

Epidemiologists support this test because it provides true data on how many people are actually infected, but unaware they have COVID-19, Dao said.

“We are in severe shortage of nasopharyngeal testing kits,” he said. “This serology testing may take off some burden of people who have mild symptoms for one to two weeks weeks, rush to the emergency room and ask for testing of COVID19. We just like to give people another option, and give the people more information about their infected status. We are not trying to replace the standard of care.”

‘People are really scared’

Still, other physicians worry.

“People are really scared. We’re in an environment where there’s a lot of information and misinformation, a lot of high stress and anxiety,” said Jon Quach, an assistant professor in the internal medicine department at UCLA’s David Geffen School of Medicine.

At hospitals such as UCLA’s, patients who get coronavirus tests are carefully screened. The medical team includes experts in infectious disease, epidemiology and public health. It takes clinical expertise and knowledge to administer non-FDA approved rapid IgG/IgM tests and then process the results in an effective matter, said Quach, speaking for himself and not the university.

It’s not clear how much assistance Dao is getting on those fronts. Quach worries that a patient in the early stages of infection could get a false negative, then go visit an elderly relative, spreading the disease quickly through a very vulnerable population.

False positives are also possible if someone had been exposed to a different coronavirus.

“Our role as physicians is to ensure the well-being of our communities, and one of the first pillars of being a doctor is, ‘Do no harm,’ ” Quach said.

No FDA objections

The serology tests are not illegal, and the FDA said it “does not intend to object” to their development and distribution by commercial manufacturers, so long as the FDA is notified and patients understand that the test isn’t FDA approved.

That means those like Dao must include a long list of disclaimers in offering the test — including that negative results don’t necessarily rule out coronavirus infection, and that follow-up testing with the molecular diagnostic should be considered to rule out infection for those who’ve had contact with the virus.

Dao’s clinic has included the FDA disclaimers on its Facebook page listing the serology test services.

Many feel that, since molecular testing is in such short supply, the blood tests are worth a try.

Last week, at the request of Colorado Gov. Jared Polis, Denver-based AYTU BioScience won emergency-use approval from the FDA to import 100,000 serology test kits from China.

Different purposes

The CDC uses, and currently recommends, PCR testing to diagnose coronavirus infection. PCR is a very sensitive test, but combining it with serology testing would theoretically increase the sensitivity of testing even further. “Having two tests would allow confirmation of infection, rather than relying on a single test,” according to the Center for Health Security at Johns Hopkins University.

Serology tests were used in past coronavirus outbreaks — SARS and MERS — but were time- and resource-intensive to create because proper animal models, protocols and specific antibodies had to be developed, the university said.

As it stands, the blood antibody test has a completely different purpose than the PCR tests, Philip L. Felgner, director of UC Irvine’s Vaccine Research and Development Center and Protein Microarray Laboratory and Training Facility, told SCNG.

While the PCR test can diagnose active virus in patients, the serology test allows public health officials to measure its spread in the wider community.

Serology tests can find otherwise-healthy people who are carriers of the virus. That, in turn, allows public health officials to wield more of a chisel than a sledgehammer, pinpointing exactly where infections are spreading and issuing intense shelter-in-place measures in those specific communities, rather than across an entire state the size of California.