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A false positive Covid-19 test result ... test might be a false positive, get it confirmed with a PCR test, Dr. Redel says. ... of the test’s ability to detect dead virus particles weeks after ...
False positive COVID-19 tests—when your result is positive, but you aren’t actually infected with the SARS-CoV-2 virus—are a real, if unlikely, possibility, especially if you don’t perform ...
The accuracy of PCR tests varies, depending on when someone is tested. However, one study found that the false-negative rate can be as high as 20 percent when a person is tested five days after ...
Accuracy is measured in terms of specificity and selectivity. Test errors can be false positives (the test is positive, but the virus is not present) or false negatives, (the test is negative, but the virus is present). [179] In a study of over 900,000 rapid antigen tests, false positives were found to occur at a rate of 0.05% or 1 in 2000. [180]
In reality, the reverse transcription polymerase chain reaction (RT-PCR) test for SARS-CoV-2 is highly sensitive to the virus, and testing laboratories have controls in place to prevent and detect contamination. [215] [216] However, the tests only reveal the presence of the virus and not whether it remains infectious. [215]
Second, the person with a positive Antigen-RDT could be asymptomatic but a "contact of a probable or confirmed case." [10] Nevertheless, individual countries may have different case definitions of COVID-19; for example, in New Zealand a positive PCR test (not just a RAT) is necessary for a person to be considered a "confirmed case." [11]
But if you happen to get a positive test result and you don’t have symptoms of the virus, he suggests waiting a day and testing yourself again—or calling your doctor about getting a PCR test ...
Cross reactivity has implications for flu vaccination because of the large number of strains of flu, as antigens produced in response to one strain may confer protection to different strains. [3] Cross-reactivity need not be between closely related viruses, however; for example, there is cross-reactivity between influenza virus -specific CD8+ T ...