With the LP.8.1.* variant on the way to dominance in most places, it is time to ponder which variant might drive the next wave.
The leading contenders at this point are LF.7.7.2, LF.7.9, NB.1.8.1, NY.9 (new), XEC.25.1, XFG and XFJ.
I show them here using a log scale, so you can compare their growth rates vs the most common LP.8.1.* sub-lineage: LP.8.1.1. Note the recent sample volumes are quite low, so the right side of this chart might not be a representative picture.
LF.7.7.2 is descended from FLiRT JN.1.16.1. LF.7 added several Spike mutations: T22N, S31P, K182R, R190S and K444. Then LF.7.7.2 added the Spike H445P mutation.
LF.7.7.2 has been most successful in Canada, rising to 8% frequency. The US has reported growth to 7%. But the overall growth rate appears to have slowed.
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LF.7.9 added the Spike L441R, H445P and A475V mutations to LF.7 (described above).
LF.7.9 has been most successful in Ireland, rising to 50% frequency. France has reported growth to 9%. But LF.7.9 growth seems to have slowed lately.
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NB.1.8.1 is descended from XDV.1.5.1. XDV was a recombinant of XDE and JN.1. XDE was a recombinant of GW.5.1 and FL.13.4, so this represents the last current variant with any non-JN.1 ancestry.
XDV.1 added the F456L mutation, then XDV.1.5 added G184S and K478I. NB.1 then added Spike mutations: T22N and F59S. Then NB.1.8 added the Spike Q493E mutation that characterised KP.3.1 FLuQE – an example of convergent evolution. Finally NB.1.8.1 added the A435S mutation.
NB.1.8.1 had mainly been reported from Hong Kong, rising to 80% frequency. It has also started to show signs of growth in other nearby countries, adding to its credibility.
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NY.9 is the ninth child lineage of the globally dominant LP.8.1.1. NY.9 reverts the Spike mutation to K478T.
NY.9 has been most successful in Canada (New Brunswick), rising sharply to 56% frequency. New Brunswick has dominated the recent samples from Canada. The US has reported growth to 2%, mostly reported from New York.
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XEC.25.1 adds the A435S mutation.
XEC.25.1 has mostly been reported from Singapore, rising to 36% frequency. Prior to this sub-lineage, the XEC.* variant had not been dominant in Singapore. XEC.25.1 has not gotten any traction elsewhere.
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XFG is a recombinant of LF.7 and LP.8.1.2, with a presumed origin in Quebec.
Growth of XFG accelerated in the recent US samples to 10%. Most are reported from New York and New Jersey.
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Recently classified XFJ is a recombinant of LF.7 and LS.2. LS.2 was descended from JN.1.18.5.
Starting from February, XFJ has been most successful in Spain, rising to 5% frequency.
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Little variant update: now XFJ has been designated: it is a growing recombinant displaying a set of mutations that is rapidly increasing: S:L441R S:V445P S:A475V plus S:T791A hallmark with the NTD coming from LF.7 (22N+31P+182R+190S+346T) interestingly it has T22930A to get S:F456L as XDV.1 , Eg.5.1
It’s early and hard to really tell, but I’m getting concerned about recombinant lineage XFJ designated yesterday 2 April 2025. Why? At 8 sequences, reports are from 6 countries on 3 continents with 2 US states all without travelers. It also has a breakpoint in the Spike RBD. 1/3
I will switch my pick to NB.1.8.1. It is now showing growth in multiple countries. The new recombinants XFG and XFJ are also in contention.
I will continue to monitor this topic.
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The usual caveats apply - recent sample sizes are smaller which might skew these results, and “global” sequencing data is dominated by wealthy countries, with many under-sampled regions.
I removed XFH from consideration, as it had not improved on very low frequencies.
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New round of designations for Sars cov 2 variants. Among them MV.1.1.1 is the first 456V to get 346T+445R NY.9 478T NY.10 478E NY.11 487D are LP.8.1.1 sublineages, while PD.1 is the first sublineage of the Fortaleza LP.8.1.4 , this time defined by A522P. XFL is the first ever recombinant quad
Mike Honey