“* The test can be used on day three after suspe

“* The test can be used on day three after suspected contraction of the virus.”

I have poked around the WNF site and others. My current thinking is that yes the second gen rapid antibody tests can detect lower levels of antibodies, so a positive result can be obtained on day 3 after infection.

But the question then is, is day 3 just the threshold for detection (some portion of the people tested will have sufficient antibodies to test positive on day 3 and the others will not)?

Or will every infected person test positive on day 3? If every infected person will test positive on day 3 and they become contagious on day 4, then there is not a 3 day window, just a 1 day window.

However, based on what I have read, I go with the first answer, some of the infected people will test positive on day 3, but others will not test positive until day 4, day 5, or later.

The following is a French study published on May 14, 2020, “Biotime SARS-CoV-2 IgG/IgM Rapid Qualitative Test got excellent performance results compared with other maunfacturers in the evaluation study of Amiens University Medical Center in France!”

http://www.biotime.cn/En_Ne_d_gci_85_id_51.html

Per the graphs in the study, the Biotime test only has a sensitivity of 12-30% during the first couple of days. Per Table 1, sensitivity was 12% on day 3 and 100% sensitivity was not achieved until day 15.

Test sensitivity is the ability of a test to correctly identify persons with infection, whereas test specificity is the ability to correctly rule-out infection.

To me, using a rapid antibody test to screen people for recent infection, will only identify on day 3 some of the infected people (positive test), but a majority of the infected people will still test negative on day 3 and possibly for several days beyond. Those stilling testing negative on days 4, 5 and later will probably be contagious, but will still gain entry to the venue, which is what your testing is trying to avoid.

So using a rapid antibody test could partially reduce the number of infectious people enter a venue, but is the reduction sufficient to allow authorities to approve such a plan? To me, probably not.