It is extremely unlikely for the covidSHIELD test to produce a false positive result. In a recent study, the saliva test was shown to have a specificity of 98.9% and a sensitivity of 95.8% which makes it one of the most accurate tests in the world. SHIELD Illinois has had no confirmed false positives in the hundreds of thousands of tests that have been performed. We have, however, had positive cases detected before the onset of symptoms. This is one of the strengths of the covidSHIELD test. If a person is going to experience symptoms, the symptoms usually appear within 4-7 days after exposure. Unfortunately, an infected person usually starts shedding the virus (is contagious) 3-5 days after exposure. This means there is at least 24-48 hours where a person is highly contagious but has not outward symptoms. In the absence of regular PCR testing, an person infected with SARS-CoV-2 can be infecting others without even knowing they are infected themselves. The covidSHIELD test administered by SHIELD Illinois can detect the virus as early as 2-3 days after exposure.