The Delta Variant is now dominant in the USA.
It is rapidly increasing its share of new cases, although overall COVID case numbers remain low.
As of the 3 July bi-weekly report from the CDC, Delta accounted for over half of new cases (51.7% of sample, up from 30.4% on the prior bi-weekly report).
The Brazilian Variant (P.1, or Gamma), no longer seems to be growing in proportion, remaining below 10% of new cases. It actually dropped one percent, to 8.9% on this report, from 9.9% on the prior report (19 June).
The UK variant (B.1.17, or Alpha) is fading fast, as Delta takes over. It is now around 28.7% of new cases, down from around 70% in May, and 44.2% on the last bi-weekly report (19 June).
Lambda (Peruvian) is still too rare in the USA to even make the list.
I just admitted my sickest covid in months. Not vaccinated
Thanks for your great reports and updates Beau.
The R0 for the Delta variant is estimated to be between 5 and 8 (https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/997418/Variants_of_Concern_VOC_Technical_Briefing_17.pdf) though judging by the distinction from earlier variants with R0s estimated to be between 4.5 and 5.3, I would guess that R0 is pushing much closer to 8 than 5. Compare that with the R0 of the April 2020 variant of 2.5 or the original Wuhan virus R0 of 1.3. This thing has come an incredibly long way in a relatively short period of time. Based on this data, Delta is almost certainly going to take over new cases around the world.
That may actually be good news. Looking at the UK data linked above, Delta is about 1/2 as likely to result in people over 50 being admitted to the hospital overnight and 1/4 as likely to result in death. I’m not sure how much of the results are confounded by vaccination (they don’t give a breakdown of who among the admitted and dead are fully vaccinated), but any time we see significant reductions in hospitalizations and deaths, that’s a good thing.