Question: Wondering how test results are being filtered, that is, can an individual know which variant they are infected with based on the test they use? Do home tests reveal the variant and are home testers obliged to report which one they have?

Answer: The tests we use to detect SARS-CoV-2 infection (both at-home and lab-based) are not designed to identify which variant a person is infected with.  We can, however, make informed assumptions about which variant a person is infected with thanks to genomic sequencing.  Specifically, CDC identifies and tracks variants using the national genomic surveillance system, which collects and analyzes positive specimens from a large group of labs across the country participating in the National SARS-CoV-2 Strain Surveillance (NS3) program.  CDC’s NowCast model uses data from the surveillance system to estimate current proportions of circulating variants by location.  As Figure 1 shows, an estimated 98% of all recent/current cases are driven by omicron (95% CI: 97%-99%).  In terms of at-home tests, folks are not required to report the results (see Q&A of 11/16/21), which means that a large number of cases are likely not being captured in the case counts we’re seeing. 

Figure 1. Nearly all cases are driven by Omicron; NowCast Estimates of Circulating Variants (from CDC)