A Garden  Grove physician is likely one of the first practitioners in the U.S. to begin offering a rapid  coronavirus screening test popular in Asia that can provide results within 10 minutes through a simple fingerstick.

Dr. Michael Dao, a 55-year old internist who operates the Dao Medical Group in Little Saigon, in the past two weeks has administered 180 COVID-19 IgG/IgM Rapid Gold tests provided by PCL Inc., one of the largest biotech firms in South Korea.

Three people tested positive for COVID-19 but did not display any symptoms and were instructed to self-quarantine, Dao said, adding that the results were reported to the Orange County Health Care Agency.

Dao expects delivery Thursday of 10,000 more test kits and then another 2,000 within the next few days.

“Emergency situations call for emergency measures,” said Dao, who has offered to donate 50,000 additional tests to Orange County and the state for public service employees vulnerable to COVID-19, including postal workers, police officers and first-responders.

Dao said several Orange County physicians have contacted him about providing them with kits that can only obtained through a licensed importer.

The rapid result serology test is already used widely throughout Asia to detect coronavirus and is beginning to make inroads within the U.S.

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

The FDA has said it “does not intend to object” to the development and distribution of blood tests for COVID-19 by commercial manufacturers, so long as the FDA is notified and patients understand the test hasn’t been reviewed by the FDA.

Those administering the tests also are required by the FDA to inform patients that negative results don’t rule out coronavirus infection, particularly in those who’ve been in contact with the virus; and that follow-up testing with a molecular diagnostic should be considered to rule out infection for those who’ve had contact with the virus.

“Results from antibody testing should not be used as the sole basis to diagnose or exclude” coronavirus infection or to inform infection status, the FDA said. Positive results could be due to past or present infection with other coronavirus strains.

The Dao Medical Group has included the FDA disclaimers on its Facebook page listing the serology test services.

Serology vs. PCR testing

Serology testing is relatively simple and requires only a single drop of blood through a fingerstick, just like checking for blood sugar in patients with diabetes, Dao said. The blood is placed in the reservoir of the test kit’s cartridge. Then two drops of solutions are placed in the same reservoir. Test results are available in about 10 minutes.

Individuals are required to park behind Dao’s office and remain in their vehicles while his staff conducts the test.

The test administered by Dao is different from the most common COVID-19 detection procedure called polymerase chain-reaction testing, or PCR. That test uses a cotton swab, like a giant Q-tip, to collect samples from the nose or throat, then examines the genetic material for the virus’ specific markers.

Most testing in the U.S. is done this way, and the 16 labs that have received emergency use authorization from the Food and Drug Administration are supplying PCR tests.

The other, called a serology test like the one administered by Dao, checks the blood for antibodies that battle the coronavirus and is more common in China, Singapore and South Korea.

“It’s a good tool for people with no symptoms or minimum symptoms who may be unaware they have been infected,” Dao said.

Each test has its advantages and disadvantages, experts say. The blood test can spot antibodies in people who had mild symptoms and have recovered — valuable to public health officials trying to assess how widely the virus has truly spread — while PCR tests detect only active disease in the nose and throat. PCR tests can’t determine if a person had a mild case of COVID-19 and then recovered.

But both tests can miss the virus if taken too early. PCR tests can produce false negatives if taken before the viral load gains sufficient mass; and blood tests can give false negatives because it can take the body a week or so to produce enough antibodies to register.

The Centers for Disease Control said initial work to develop a blood test in the U.S. is underway, but that will take some time.

Testing and early detection

There’s an important public health role for serology testing, but it’s different than PCR’s role, said Philip L. Felgner, director of UC Irvine’s Vaccine Research and Development Center and Protein Microarray Laboratory and Training Facility.

“There are a lot of infected people who are asymptomatic out there spreading the virus, and that’s what’s causing this outbreak,” Felgner said. “We don’t have enough PCR tests to detect sick people right now, much less asymptomatic people, so asymptomatic people are passing the infection on to their close contacts.

“We need a test that we can use on healthy people to find out who is a spreader of this virus, and that’s where the antibody test would be useful. It has a completely different purpose. If a person is trying to sell the antibody test for clinical diagnosis, it’s definitely not approved. It’s not for that purpose.”

Felgner is working on research using serology testing on blood samples from Washington state, where COVID-19 first erupted in the United States, to determine how widespread the infection really is in the community.

“What we need to do with the serological tests is survey locations to find out how much intensity of the virus is in an environment,” Felgner said. “If we go into New York City right now and just measure average people in the community, their antibody responses are going to be elevated compared to someplace like Nebraska, where nothing seems to be occurring.

“That’s what the serological test is good for. It doesn’t need to be FDA approved — it’s a public health tool to determine how much is circulating in the environment.”

That tool allows public health officials to wield more of a chisel than a sledgehammer. Public health officials can use serology testing to pinpoint exactly where infections are occurring in the community, and then issue intense shelter-in-place measures in those communities.

“That’s not like what we do in the U.S., where all of California is on shelter-in-place,” Felgner said. “It probably isn’t necessary all over, but we’d need to have a test to know where the outbreaks are.”

That’s where the serology tests are most useful, he said.

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