San Francisco Chronicle
Quick testing remains scarce
Supplies, cost inhibit scaling of diagnosis tool
Two weeks ago, a 68-year-old man came into a Fairfield emergency room complaining of body aches that’d been bothering him for four days.
Hospital staff swabbed his nose and processed the sample immediately on-site, using a machine that confirmed within the hour that the man was positive for the coronavirus. The fast results let doctors know that the patient — who also had diabetes and heart disease — was a good candidate for monoclonal antibodies, an intravenous treatment for high-risk COVID patients that works best when given within the first week of symptoms.
“Knowing the patient had symptoms for four days meant that if we got an answer earlier, we could immediately start monoclonal antibody therapy,” said Dr. Caesar Djavaherian, the emergency physician who treated the man. “If we’d sent the (sample) to the lab, and it typically takes two or three days to get results back, they probably
would’ve been outside the window of therapy.”
Polymerase chain reaction, or PCR, tests — the type that Djavaherian used — are considered the highest quality coronavirus test. These molecular tests amplify genetic material many times over in order to detect the virus’s presence. This is more accurate than the rapid antigen tests like BinaxNow or Ellume that can be done at home, like a pregnancy test, and detect viral proteins. But normally, as Djavaherian noted, PCR lab tests take at least a day to return results — a critical window in which an infected person may not take sufficient precautions to protect others, or a COVID-negative person may lose in unnecessary quarantine.
And so, some hospitals are using machines that produce accurate results within 45 minutes, like the test used for the Fairfield patient, made by the diagnostics company Cepheid. Rather than being sent out to labs, the samples are processed on-site by a piece of equipment that can be as small as a desktop printer. Another commonly used rapid molecular test, Abbott ID Now, generates results in about 20 minutes. The ID Now is similar to PCR in that both amplify viral genetic material, but with different technology. An Abbott spokeswoman said the company is selling the machines for no more than $4,500 apiece.
It seems like the best-case scenario: a highly accurate test that returns results quickly. In the case of the Fairfield hospital, it allowed a patient to get time-critical monoclonal antibodies the same day — and he responded well, Djavaherian said.
So why aren’t these fast, accurate tests more common in settings like schools, clinics and workplaces, many of which require people to confirm their COVID status using lab tests?
There are several reasons, Bay Area experts say — including supply constraints, cost, staffing demands, and because rapid molecular tests are hard to scale up efficiently.
The best test, experts say, depends entirely on your goal: Is it to diagnose a sick patient quickly to start treatment? To screen hundreds of asymptomatic people so they can go to work? To get cleared to fly, go to camp or a concert?
As hospital leaders, school officials, office human resources managers and consumers attempt to incorporate testing into their routines for months if not years to come, they’re learning there is no one perfect test for all occasions. A test that works well in a hospital for a few patients at a time doesn’t always translate to mass testing operations.
It’s a challenge inherent to building an unprecedented testing infrastructure that touches virtually every part of people’s lives — and affects settings that usually are not intensely involved in health care, such as schools, workplaces, airports and homes.
“It’s been fascinating to see all the differences, the scaling up of what is one of the largest health care delivery programs happening outside of health care right now,” said Caroline Savello, chief commercial officer at Burlingame company Color, which is providing testing for thousands of schools and businesses in California and elsewhere, including San Francisco Unified School District.
Some providers say the rapid molecular testing machines aren’t in short supply, but the test cartridges are getting harder to obtain as demand soars for all types of testing.
The San Francisco-based urgent and primary care network Carbon Health uses the Abbott ID Now test in its dozens of clinics, and for schools and business with whom they contract to provide frequent testing.
“In the summer we had ample supply of the Abbott ID Now point-of-care test,” said Djavaherian, the emergency physician who also co-founded Carbon Health. “Starting six weeks ago we started to see a lot of strain on the supply of the test.”
Carbon plans to add the Cepheid test in the next month to accommodate the high demand in rapid tests, and to prepare for flu season. The Cepheid system can test for COVID, respiratory syncytial virus and the flu at the same time.
“That was the initial reason we started to explore it,” Djavaherian said. “And as (COVID) cases spiked over the past two months we realized we also need to have a diversified supply chain.”
The Abbott ID Now machine, which some hospitals use in their emergency department, is the size of a toaster oven. Because the machine must be supervised by an entity affiliated with a federally certified lab, schools or businesses cannot use it unless they partner with such an entity, said Dr. Jeanne Noble, director of COVID response at UCSF’s Parnassus emergency department, which has four Abbott ID Now machines.
And each test must be done one at a time by a staffer who handles the sample manually. That works if a few or even a few dozen sick patients get tested in the emergency room throughout the day. So UCSF’s four Abbott machines, for example, allow it to run four tests every half-hour. Most PCR lab tests, by contrast, get sent to labs and are processed by automated systems that run hundreds of samples at a time.
“If you’re doing 3,000 tests a day, it’s hard to imagine 3,000 cartridges, you have to pipette into each cartridge,” said Dr. James Zehnder, director of clinical pathology at Stanford Medicine, which runs 100 to 200 Cepheid rapid tests a day, mostly in the emergency room and for patients right before urgent operations. “That kind of supply chain doesn’t exist and it’s a very inefficient and expensive way of doing testing. We reserve it for situations where we truly need rapid turnaround time for clinical decision-making. Otherwise, 12 to 24 hours, or even two days, is fast enough turnaround time for most outpatient screening.”
Even though lab tests take longer to report results, they’re more efficient when testing lots of people frequently. SFUSD, for example, tests staff using a LAMP test, which is similar to a PCR test. Teachers and staff self-swab, and drop the samples in a bin. Those samples are sent to Color’s lab in Burlingame, and results come back within 24 hours, said Savello of Color, which is providing testing for the school district. The self-swab eliminates the need for a health care professional to be there to do it.
“We’re reducing costs and overhead of testing programs when doing it this way,” Savello said.