XBB.1.16 is the second most common variant in the US

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XBB.1.16 has debuted on the CDC Covid variant list today in SECOND PLACE.

XBB.1.16 is already estimated to be responsible for more than *seven percent* of Covid cases in the US.

The XBB.1.16 variant, which wasn’t even listed on last week’s CDC variant list, has been separated out from other variants for the first time by the CDC today.

As per the CDC:

CDC Nowcast projections* for the week ending April 15, 2023, estimate the proportion of these lineages designated as Omicron with estimates above 1%: XBB.1.5, XBB.1.16, XBB.1.9.1, XBB.1.9.2, XBB.1.5.1, FD.2, and BQ.1.1.

XBB.1.5 is projected to be at approximately 78.0% (95% PI 73.6-81.8%).

XBB.1.16, XBB.1.9.1, XBB.1.9.2, XBB.1.5.1, FD.2, and BQ.1.1 are projected to be between 1.0% and 7.2% of circulating lineages.

XBB.1.16, XBB.1.9.1, XBB.1.9.2, and XBB.1.5.1 all have positive growth. XBB.1.5, FD.2, and BQ.1.1 are all decreasing in proportion. All other virus lineages are predicted to have very slow or no change in proportion.


CDC: List of Covid variant proportions


XBB.1.16 is now widely distributed across the United States:


The XBB.1.16 variant, also referred to as Arcturus in some media outlets, has been wreaking havoc in India, with a sudden surge in cases recently – see our Twitter feed for recent news about the variant in India.

In Singapore, which also has a considerable number of XBB.1.16 infections, about 30 per cent of new Covid infections are thought to be reinfections.



We will be updating this post as more information about XBB.1.16 in the US becomes available.



Deltacron recombinant XBC.1.6 at 30% of sequences in South Australia



** This post was originally published on April 14, 2023 **