John McMullen: The folly of false positives, shaming and competitive balance
Philly Voice discusses the effectiveness of available COVID-19 tests according to HSS infectious disease specialist, Andy O. Miller, MD.
Dr. Miller explained no test is completely accurate even when administered properly, however some tests are pretty good. “PCR tests are most accurate when the amount of virus is highest: in early symptomatic infection, and in early pre-or asymptomatic infection too,” he said. Dr. Miller added, “The nasopharyngeal swab (all the way to the back of the nose) is probably the most accurate sample," however, "there are promising tests using mid-turbinate nasal swabs (halfway back the nose), nasal swabs (front of the nose), and oral/saliva samples."
Dr. Miller said true-false positives are rare and can be broken down into two types: a “true” false positive, when the patient has no virus, never had virus, and the positive test is random; and a remnant of a prior infection, which seems common. "Someone has COVID-19, symptomatic or otherwise. The infection passes; they’re fine, and their body even produced antibodies. But the PCR test can remain positive – maddeningly – for weeks. Often it’s only intermittently positive – one day negative, the next positive – and almost always at very, very, very low levels of virus. These aren’t really false positives, but they are misleading because they almost never represent new, active, transmissible, contagious COVID-19,” said Dr. Miller.
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Additional coverage: PhillyVoice.com.