Advanced Stanford blood test reveals if you’ve been exposed
Crowds flock to test sites to learn if they have antibodies to coronavirus and thus may be immune
Long motorcades of volunteers converged at three Stanford University research sites last week, donating blood for a new test that identifies the prevalence of the coronavirus in our community — and could help reveal the full scope of Santa Clara County’s epidemic.
In the first large-scale study of its type in the U.S., the 2,500 test slots Friday and Saturday filled up within hours, as news of the project spread quickly through the county.
The test detects protective antibodies to the virus rather than the virus itself.
This gives scientists a snapshot of how many people in the county have been infected but weren’t seriously sick and didn’t realize it. And it tells residents whether they carry potentially protective antibodies — and so may be immune to future infection.
“This is critical information,” said principal investigator Dr. Eran Bendavid, an infectious disease specialist and professor of medicine with Stanford Health Policy.
“We will show the country what to do and how to do it.”
The project, coordinated with the Santa Clara County Department of Health, can guide public health measures and policies, showing where the epidemic is heading, when it is safe to lift shelter-in-place restrictions, and how far we are from “herd immunity,” when it becomes harder for a virus to spread.
The new test finds antibodies in the blood — molecules made by the immune system — in response to a viral attack.
Even though the pathogen is new, scientists have discovered the two antibodies — called IGM and IGG — that are triggered by infection and have built a test that detects their unique signature.
Because the COVID-19 virus may cause few or no symptoms, many people don’t know they’ve been infected. Or perhaps they were mildly ill before COVID-19 made headlines and simply dismissed it as a cold or flu.
This approach, called a “serological test,” remains a research tool and is not yet widely available in the United States.
Commercial development is underway, but supplies are limited, slowing the rollout.
The Food and Drug Administration last week approved a test by Cellex, based in Research Triangle Park, North Carolina. There’s also a Mayo Clinic test in the pipeline.
Once it is mass-marketed, experts say the test will be easy, cheap and very different from current diagnostic tests, which use throat swabs and an expensive technology called Polymerase Chain Reaction to find genetic evidence of infection.
There is a major shortage of these tests, so many people never learn if they’re infected.
At three churches — two in San Jose and one in Mountain View — long lines of vehicles snaked into parking lots and motorists rolled down their windows and offered a finger.
The pinprick took just a moment.
Teams of Stanford medical students, nurses, physician assistants and other staff scurried around each site, directing traffic and processing every sample. Volunteers got a $10 Amazon gift certificate for participating.
“It’s an opportunity for me to know if I’m positive for the antibodies — and it’s very important for the community to know how many people have been unknowingly infected,” said Linda Sanders of Los Altos, who arrived for an early morning test in Mountain View’s First Presbyterian Church.
Laura Forrest of Palo Alto, a health care worker, said she volunteered because “Stanford is a great facility and I want to support them.”
She also sought to learn if she acquired antibodies from recent on-the-job exposure. “I would like to return back to working,” she said. “Having this information would be very important to me.”
If positive, they’ll get results in several days. If negative, they’ll get no news.
A positive result means they had the virus and recovered. It also could mean they are currently infected and could still transmit the disease.
Antibodies act like sentinels of disease, launching an immediate response if a familiar virus returns. They’re normally produced in a person’s body around seven to 10 days after the initial onset of a virus.
The IGM antibodies generally are detectable in blood several days after initial infection, although levels over the course of infection are not well-characterized.
The IGG antibodies become detectable later after infection. Positive results for both IGG and IGM indicate recent infection.
It is not yet proven that these antibodies provide protection. Related coronaviruses offer a spotty record. Some, which cause the common cold, return again and again. The antibodies to Middle East respiratory syndrome lasted merely a year.
But there are promising clues that COVID-19 might act like its closest cousin, the SARS virus, which triggers an immune response that persists for at least three years. In a Chinese study of rhesus monkeys, COVID-19 antibodies protected the animals from a second infection.
If protected, people could potentially return to work. There also is the prospect that the antibodies could be used as therapy against the disease.
Dozens of companies are working to develop antibody tests, as are researchers at the Centers for Disease Control and Prevention.
In March, New York City’s Icahn School of Medicine at Mount Sinai started a website where scientists can order the chemicals, other lab ingredients and standardized protocols needed to get tests up and running.
A similar strategy will soon be deployed in the small Colorado ski town of Telluride in partnership with the pharmaceutical company United Biomedical Inc. and its subsidiary c19. It will test all 8,000 of its residents for free, starting with health care workers, first responders, teachers and their families.
The town was chosen because c19’s co-founders have a home there.
“When we reported this in our county meeting, the entire team cried,” Dr. Sharon Grundy, medical director of primary care at the Telluride Medical Center, said in a statement.
The test also is being deployed in some countries in Asia.
Until commercial tests are widely available, Bay Area residents urged that Stanford’s research be expanded to more residents in Santa Clara County, as well as adjoining counties.
“There is so much mystery and uncertainty around the virus,” said Susie Richardson of Palo Alto. “Participating in the study might be a way to both contribute to what we know and to possibly learn something about myself.”