How Much COVID Testing Is Just Right?

Santa Barbara Doctor Works to Find the Answer

Dr. Stewart Comer, head of Cottage Health’s Pacific Diagnostic Labs. | Credit: Nick Welsh

If people who’ve already been vaccinated can still get — and still transmit — the Delta variant, thus infecting others without knowing it, shouldn’t everyone, vaccinated and unvaccinated alike, be required to get tested to ensure workplace safety? This question was posed last Tuesday, August 31, when the Santa Barbara County Board of Supervisors adopted a policy mandating all 4,600 county employees to either be vaccinated or be regularly tested. Vehemently opposing this policy was a room full of vaccination skeptics, civil libertarians, and self-styled conscientious objectors.

“That’s a good question,” answered Mona Miyasato, the county’s CEO. “That’s a great question,” added Dr. Stewart Comer, head of Cottage Health’s Pacific Diagnostics Lab (PDL), just a few days later. But according to both Comer and Miyasato, the answer is that universal testing is not needed at this time.

Here’s why: The vast majority of people testing positive, getting sick, and being hospitalized have not been vaccinated. The number of breakthrough cases — in which vaccinated individuals test positive — still remains relatively low. The case rates per hundred thousand for the unvaccinated in Santa Barbara County hover about 4.5 times higher than those who’ve gotten their shots. For vaccinated workers, Miyasato said, tests would only make sense if they were exhibiting symptoms of COVID; either way, all county employees would be required to wear masks.

In the health sector, however, the rules are more stringent. As of September 30, all health-care providers in the State of California must be vaccinated. Regular testing will not be an option.

Dr. Comer, a medical pathologist and 30-year U.S. Navy veteran, finds the question a difficult one to answer. “We know people who are vaccinated are getting infected. We know the vaccine is not fully protective. We know that right now this involves a relatively small number of people. The question then becomes ‘Should everyone get tested?’” he asked. “In a way, it comes down to a matter of supply. If everyone got tested, what would happen to the supply chain? Do we have the resources? We’re never going to get to a COVID-Zero.”

“Is the answer the booster shot?” Comer asked. “At what point do the vaccines lose their efficacy and boosters make sense?” The answer to both is “I don’t know.” What worries Comer most, however, is if the virus mutates so many times that the tests are no longer accurate. “But we’re not there yet,” he says. “That’s why people are spending so much time on this.”

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Comer’s immediate concern is Cottage Hospital and all the patients and workers who go in and out. “People need to have 100 percent confidence we’re protecting everyone within our four walls,” he said. In that context, Comer addressed several comments he heard at last week’s supervisors’ meeting questioning the accuracy of the standard PCR (polymerase chain reaction) test. One speaker argued that as many as 90 percent of the test results were “indeterminate.”

“I can tell you it’s not accurate at the hospitals served by our lab,” Comer stated. PDL only recorded 53 indeterminate readings in the past year. “That’s .03 percent. Every time a case comes up “indeterminate,” Comer stressed, the patient is re-sampled and the genetic material re-tested on a different, independent testing platform.

PCR testing is not a simple yes-or-no equation. For patients who have not adequately blown their noses before, for example, an abundance of nasal mucous can interfere with the test. With COVID, the virus can take up to seven days to incubate in the body. If a person is tested too soon, a positive person could test negative. And PCR testing is so sensitive that it can pick up even a small remnant of the virus — well after a person is no longer infectious. Complicating matters even more, COVID sheds its viral loads at unpredictable rates. The intensity of infection often has little relationship to the intensity of symptoms displayed.

The situation improved significantly in the third quarter of last year with the introduction of the newer, cheaper, and much faster — 15 minutes — antigen home test kit. This registers the presence of antigens that trigger the body to fight the infection. The antigen test, however, fails to pick up very recent infections, so it poses a significant risk of false negatives. But positive results from an antigen test means the person is definitely infectious.

When the COVID curtain first descended, Comer said, PDL could test maybe a dozen samples a day. Today, he and his team can handle 2,000.

And then there are the point-of-care tests — PCR tests that can be finished in 15 minutes — administered to anyone and everyone entering the Emergency Department whether for COVID-related symptoms or something else. Staff members are tested twice a week. And patients are tested every five days as a precautionary measure to ensure they didn’t contract it while under the care of Cottage. 

The public at large, Comer said, does not see how hard the clinical lab technicians work to keep the testing labs humming seven days a week. “These are the unsung heroes,” he said.

Correction: This story now correctly discerns between ‘antigen’ and ‘antibody’ in the testing realm.

At the Santa Barbara Independent, our staff continues to cover every aspect of the COVID-19 pandemic. Support the important work we do by making a direct contribution.


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