In the majority of cases, the DNA of viruses is only detected when we are infected with them and they are still reproducing and spreading through our respiratory tracts. '&l=' + l : ''; By signing up, you agree to Pedestrian Group's Terms of Service and consent to our Privacy Policy. It's essentially a test for the test to see if it's working as it should, it's controlling the test. Summary. for (var t=0; t