Rapid Antigen Tests and RT.PCR - Collected At Home
It is time to request more free covid rapid antigen tests from the gov't this week. I just reviewed a study pre-print comparing the Rapid Antigen Tests (3 manufacturers) and RT.PCR tests to compare the sensitivity of the results when their isolated sequenced virus was either the delta variant or the omicron variant. The study was conducted by NIH, FDA, and the UMass Chan Medical School. All of the subjects were part of a very large "at home testing program" and there were >5000 participants enrolled in the study between Oct 18, 2021 and Jan 24, 2022. All of the subjects collected 2 nasal samples every other day for 15 days - nasal swab collections were separated by at least 15 minutes. RT-PCR tests were all sent to and performed by the same lab. The "at Home tests" were read by the subjects and the information submitted to the study coordinators.
153 subjects developed +RT-PCR tests (61 delta, 92 omicron) during the study and 24% of subjects had a +rapid antigen test on the same day. There were then increases in the number of + antigen tests over the next days demonstrating that the test picks up Covid-19 cases as the amount of the virus increases and the period of infectivity begins. There was no significant difference between the data for delta vs omicron virus samples which was one of the important questions about the variants tested in this study. See Below
There are a number of rapid at home antigen tests that are approved by the FDA. In this study the 3 manufacturers for the tests were BD Veritor At Home Covid-19 Test, Quidel Quick View At Home OTC Covid-19 Test, and Abbott BinaxNOW Covid-19 Antigen Self Test. It is important to make sure that the tests have not expired when you start to use them, and to follow the instructions carefully. My 10 year old grandson collected my nose samples and added the swab to the container - under the supervision of his MD uncle. I was one of many he did that morning when our family was together and I was impressed. If you have symptoms and the test is negative, repeat it in 1-2 days when the amount of virus might have increased. And if you are doing the test to make sure you are NOT infected, perform the test immediately before going out, especially to visit susceptible people. The tests can rapidly become positive - testing in the morning for an evening party may be too long before the event.