It depends where you live. The UK was an early[0] leader in sequencing a lot of their cases. They hit 600,000 sequenced cases in July[1]. That said, if you jus

It depends where you live. The UK was an early[0] leader in sequencing a lot of their cases. They hit 600,000 sequenced cases in July[1]. That said, if you just want to know what proportion of the population has delta, you don't need to sequence that many cases. The point of sequencing a large fraction of cases is to catch emerging variants, that wouldn't be likely to be caught otherwise. But to know whether Delta is 30%, 50%, or 70% of cases, you just need a good random sample, not a particularly large one, and I imagine you can do that at the labs where the PCR tests are being run. (at one point, I recall that the UK had a test that matched on three distinct sites on the virus, and they found that one of those sites would turn up negative for a particular variant, so they were able to use that as a proxy for the spread of the variant. I don't remember if that was Alpha or Delta though, and obviously it's no replacement for sequencing) [0] https://cen.acs.org/analytical-chemistry/sequencing/200000-counting-UK-sequenced-cases/99/web/2021/02 https://cen.acs.org/analytical-chemistry/sequencing/200000-c... [1] https://www.gov.uk/government/news/uk-exceeds-600000-covid-19-tests-genomically-sequenced https://www.gov.uk/government/news/uk-exceeds-600000-covid-1...