“At the moment, the United States has no semblance of public-health testing” for the coronavirus, says Michael Mina, an assistant professor of epidemiology at both Harvard Medical School and the Harvard T.H. Chan School of Public Health. What does Mina—an expert in viral testing protocols—mean by that?
Current tests for active infection with SARS-CoV-2 are highly sensitive—but most are given to suspected COVID-19 patients long after the infected person has stopped transmitting the virus to others. That means the results are virtually useless for public-health efforts to contain the raging pandemic. These PCR (polymerase chain reaction) tests, which amplify viral RNA to detectable levels, are used by physicians, often in hospital settings, to help guide clinical care for individual patients. In general, members of the public have not had access to such tests outside clinical settings, but even if they did, would find them too expensive for frequent use.
Furthermore, such tests detect tiny fragments of viral RNA even after the patient has recovered. Mina says that means “the vast majority of PCR positive tests we currently collect in this country are actually finding people long after they have ceased to be infectious.” In that sense, a positive result can be misleading, because the results can’t be relied on to guide the epidemiological efforts of public-health officials, which are focused on preventing transmission and controlling outbreaks: “The astounding realization is that all we’re doing with all of this testing is clogging up the testing infrastructure,” with results arriving a week or more after tests are administered, “and essentially finding people for whom we can’t even act because they are done transmitting.” In fact the testing backlog is so dire, and so “absolutely horrendously useless as a system for public-health surveillance,” that Mina believes the United States should at the very least throw away the millions and millions of samples that are waiting to be tested—and perhaps even halt the current testing regime and just start over.
“We need to change the whole script of what it means to test people,” he says. “In our country, we have always assumed that testing belongs in the clinical sphere, in the diagnostic sphere, and has to be run by laboratories or diagnosticians. The result is that we have a system for coronavirus testing…which is flailing, with raging outbreaks occurring.” What the country needs instead are rapid tests, widely deployed, so that infectious individuals can be readily self-identified and isolated, breaking the chain of transmission.
To do that, Mina says, everyone must be tested, every couple of days, with $1, paper-based, at-home tests that are as easy to distribute and use as a pregnancy test: wake up in the morning, add saliva or nasal mucous to a tube of chemicals, wait 15 minutes, then dip a paper strip in the tube, and read the results. Such tests are feasible—a tiny company called E25Bio, and another called Sherlock Biosciences (a start-up spun out of Harvard’s Wyss Institute for Biologically Inspired Engineering and the Broad Institute in 2019) can deliver such tests—but they have not made it to the marketplace because their sensitivity is being compared to that of PCR tests.
Mina says that is beside the point. “Imagine you are a fire department,” he says, “and you want to make sure that you catch all the fires that are burning so you can put them out. You don’t want a test that’s going to detect every time somebody lights a match in their house—that would be crazy: you’d be driving everywhere and having absolutely no effect. You want a test that can detect every time somebody is walking the streets with a flame-thrower.”
Yeah, that federal government. Always doing the right thing by the people. Yep.
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August 06, 2020 at 01:30AM
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Your Illinois News Radar » Is it time to rethink the way we're testing people? - The Capitol Fax Blog
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