How coronavirus testing will be used to reopen society

Soon, Americans may be able to drive into a pharmacy parking lot and, without a doctor’s order or delay, get swabbed for the novel coronavirus and receive their diagnosis within minutes. If they test positive, they’ll self-quarantine immediately, as will the circle of friends and family they recently came into contact with.

Many Americans — at first, perhaps just health care workers and first responders — may be able to walk into a pharmacy or hospital and get an antibody test, a pinprick blood test that will tell them if they’ve had the coronavirus and may have some immunity. If the test shows high enough levels of antibodies — proteins produced by the immune system to fight infection — they may get a certificate that allows them to go back to work.

When infectious disease experts talk about how widespread testing will need to be in place before public health officials consider reopening workplaces, schools and public spaces, this is part of the picture they paint.

It is a far cry from today’s reality in the United States. Many technological, manufacturing and scientific obstacles would have to be cleared. But steps are being taken to build up to this potential snapshot of our future. The expansion of diagnostic tests and antibody tests, also known as serologic or serology tests, will play a critical role in getting there.

“This (serology test) is ultimately a test you’re going to want to give to a lot of people,” said Dr. Robert Siegel, a professor of microbiology and immunology at Stanford. “Say you have a situation where you’re going to be in school, you might want to know what everyone in school, what their status is.”

Serology tests are blood tests that detect whether a person’s immune system has produced antibodies, which circulate in the blood, in response to infection. The presence of antibodies doesn’t necessarily mean someone is immune. But high levels of antibodies likely indicate some immunity, even if just temporarily. What is not yet clear, however, is what level of antibodies someone must have in order to be immune to the coronavirus — or how long immunity may last. Studies that try to answer these questions are either too small to draw broader conclusions or have yet to be completed, infectious disease experts say.

Medical researchers  test blood samples to find out whether someone already had and recovered from COVID-19 in Stanford University’s Clinical Virology Lab.

Some health care workers are already taking serology tests, but not yet for the purpose of getting cleared to go back to work. At Stanford Medicine, which developed its own serology test, some health care workers who had COVID-19 have taken a serology test to confirm whether they have antibodies in their blood and can volunteer to donate their plasma to help treat sick patients. But to go back to work, they must take a diagnostic test, and test negative twice in a row, said Stanford’s Dr. James Zehnder, who’s been developing both types of tests. The goal is to make diagnostic and serology tests widely available enough to administer to patients and the community at drive-through testing sites.

Debates are gaining steam around the world about how to use the results of antibody tests to put people back to work. Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Disease, said Friday it’s possiblethe United States could issue certificates of immunity — an idea that is being researched in Germany and considered in Italy and the United Kingdom.

“This is something that’s being discussed,” Fauci told CNN. “I think it might actually have some merit, under certain circumstances.”

Large swaths of the population should get serology tests to help researchers determine what proportion of the people has been infected — but not everyone needs to be tested, said Dr. Charles Chiu, a professor of laboratory medicine and infectious diseases at UCSF.

Local and national efforts to do so are already under way. Stanford Medicine, which the Stanford Daily reported administered serology tests in early April to 3,200 people in Santa Clara County, will use the results to try to learn what proportion of the population has been infected. And on Friday, the NIH announced it will collect blood samples from 10,000 healthy volunteers to study the presence of antibodies and better understand the extent to which the virus has spread.

Experts say serology tests alone cannot defeat the pandemic. Diagnostic testing must also ramp up significantly because if and when public institutions start reopening, the coronavirus will almost certainly start spreading again. Rapid diagnostic testing and contact tracing will be needed to identify and contain those flareups. California is trying to test 25,000 people a day, but so far has fallen short — testing about 9,500 people a day, on average, according to testing figures released by the state Department of Public Health.

“There’s a lot of hype about serology. I see that the use of serology in the short term is going to be relatively limited and relatively specialized,” said Dr. George Rutherford, a professor of epidemiology at UCSF. “If we’re interested in what happened three weeks ago, serology is important. If you’re interested in what’s happening today, you have to go back to (diagnostic) nasal swabs.”

Reyes tests patient Refugio Rios a test for the coronavirus.

Because the FDA is authorizing antibody tests quickly, it’s likely that the large number of companies making or trying to make antibody tests will by culled after a stricter review of test quality, experts said.

“We can’t assume for this test all of a sudden everything is going to be fixed,” said Dr. Cyrus Shahpar, a Bay Area epidemiologist who previously led global rapid response at the CDC. “There are some concerns because the FDA is letting everything go through without the normal review process, that the quality of the tests may vary.”

Widespread serology testing may not be needed if the U.S. can effectively identify small outbreaks, test and isolate those people quickly, and then identify and isolate their immediate contacts, said Dr. Lee Riley, a professor of infectious disease at UC Berkeley’s School of Public Health.

“I don’t think we necessarily need to go that route,” he said of testing broad populations of people with serology tests and issuing certificates to return to work. “If you can identify who the risk groups are now, especially when you’re past the peak, that’s when you have a chance to really study who’s still infected. You target those populations. Then it really wouldn’t matter what serology tests show.”

Widespread serology testing for humans was not deployed after the SARS and MERS outbreaks, Riley said, and is not always needed to contain infectious disease outbreaks. He pointed to public health officials’ ability to eradicate smallpox between the 1950s and 1970s, without widespread testing, by identifying small outbreaks and vaccinating people closest to the sick individual — a method known as ring vaccination, which prevents the spread from going beyond the immediate circle. That concept can be applied to COVID-19, even without a vaccine, by having people isolate themselves.

“Here we don’t have a vaccine, so what we can do is isolate,” he said. “That works. It’s a tried-and-true public health method. Tests are icing on the cake.”

But serology testing can be used to learn more about a disease. Decades ago, serology tests were given to people in Sierra Leone after a major outbreak of Lassa Fever, Siegel said. The testing revealed that there were many more survivors of Lassa fever than researchers expected — showing that the disease was a lot less deadly than they thought it was.

Catherine Ho and Mallory Moench are San Francisco Chronicle staff writers. Email: cho@sfchronicle.com, mallory.moench@sfchronicle.com Twitter: @Cat_Ho, @mallorymoench

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