San Miguel County in Colorado announced this week it plans to test everyone in the county for COVID-19. And they’ll be using a blood test rather than the usual nose-and-throat swabs.
The test typically being used at this point involves a method called PCR, which looks for pieces of the virus’ RNA in a person’s nose and throat. It only shows if someone is actively fighting and shedding the virus.
By contrast, blood testing looks for antibodies -- evidence a person’s immune system is fighting off the virus, or has already fought it off. So, it doesn’t need to be done at the moment someone is feeling ill and shedding virus. And in addition to identifying who is currently sick, it should also show who has already recovered from COVID-19.
A company called United Biomedical Inc. will do the analysis. The Colorado Sun is reporting that a couple, Mei Mei Hu and Lou Reese, are paying for the testing. They’re part-time residents of Telluride and Hu co-founded UBI.
Scientists with the company have been working on developing methods of detecting coronaviruses since at least 2004, when they wrote in the journal Emerging Infectious Diseases about an antibody test for detecting the SARS-CoV-1 virus, the coronavirus behind the 2003 SARS epidemic. (The virus currently circulating is technically called SARS-CoV-2).
In a statement, the company explained that a positive result means that a person either has COVID-19, or previously had COVID-19 and has recovered. A negative result means a person hasn’t encountered the virus (and is therefore vulnerable to infection), or they have been exposed but their bodies haven’t yet produced enough antibodies to be detected.
After getting infected, it takes about eight to 10 days for a person to produce enough antibodies for the test to detect that they are, indeed, positive.
Because of that, the county plans to retest everyone again two weeks after the first test, and in the meantime has urged people to shelter in place so they have a lower chance of picking up the virus in the interim.
“The testing alone would just give us data. It wouldn’t really have the impact it’s intended to have unless we did the shelter-in-place,” said Susan Lilly, a spokesperson for San Miguel County.
People who shelter in place and test negative both times will be considered vulnerable to future COVID-19 infection. People who test positive both times have already encountered the disease and could either be contagious, or have recovered and are no longer contagious. Lilly said if someone tests positive but doesn't show any symptoms it will be assumed they're not contagious.
County officials said the company is providing it “free of charge,” that the test is “not mandated.” The county is already testing first responders, healthcare providers and law enforcement before beginning “widespread public testing” early next week.
They cited frustration with the “extremely limited” access to testing as the main reason they partnered with a private company.
“The nose and throat swab tests are in limited supply and if we want to help slow the spread and flatten the curve, we need to use tools available to us,” said Lilly. “And we have this wonderful opportunity from people who happen to be residents here.”
On Tuesday the state health department collected nose and throat samples from residents in the area, but it was limited to 100 people and results aren’t expected back until Monday. On Friday the county said it had sent samples from an additional 41 people to labs for analysis, and that about half of the results had come back -- including the county’s first confirmed COVID-19 case.
“Our county has the rare opportunity to help slow or even possibly stop this virus locally, through the implementation of this very unique testing program and Shelter-In-Place procedures,” wrote Sergeant Dan Covault on the county sheriff’s Facebook page. “The county is asking and urging all citizens to participate in the testing, if not for yourself, then for your children, parents, loved ones and friends. The potential benefits to our community and the world as a whole cannot be overstated.”
On Monday, the Food and Drug Administration gave the go-ahead for companies and labs to use antibody tests to identify COVID-19 cases, though it says “results from antibody testing should not be used as the sole basis to diagnose or exclude SARS-CoV-2 infection or to inform infection status.”
As researchers have written, both kinds of test -- swabs and blood -- can be useful in stemming a coronavirus outbreak. In Singapore, blood testing method helped public health officials connect the dots when the virus spread from a church, to a party, and then to another church.
In Italy, scientists tested all 3,300 residents in the city of Vo. They tested each person twice (though it’s unclear which testing method they used).
“At the time the first symptomatic case was diagnosed, a significant proportion of the population, about 3%, had already been infected – yet most of them were completely asymptomatic,” the researchers wrote in The Guardian. “Our study established a valuable principle: testing of all citizens, whether or not they have symptoms, provides a way to control this pandemic.”
It also suggested the importance of people who may be spreading the virus without knowing it.
“Asymptomatic or quasi-symptomatic subjects represent a good 70% of all virus-infected people and, still worse, an unknown, yet impossible to ignore portion of them can transmit the virus to others,” they wrote. “Full testing would give us a clearer picture of how many people actually have the virus, and how many pass it on.”
According to the American Community Survey, about 8,000 people live in San Miguel County, many of them in Telluride.
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Boise State Public Radio in Idaho, KUER in Salt Lake City, KUNR in Nevada, the O’Connor Center for the Rocky Mountain West in Montana, and KRCC and KUNC in Colorado.