Convergent evolution has seen several SARS-CoV-2 sub-lineages of JN.1.* acquire the Spike F456L and R346T mutations aka "FLiRT".
Globally, JN.1.* + "FLiRT" is still showing a steady, strong growth advantage of 8% per day (58% per week) over other BA.2.86.* "Pirola" (including JN.1.*) samples, since February.
The designated lineages so far are JN.1.16.1, KP.1.1., KP.2., KR.1, KS.1, KU.2 and KZ.1.1. So 7 different evolutionary paths to arrive at the same advantageous combination, in just a few months.
It's still a bit hard to pick a frontrunner out of that swarm. My best guess is the KP.2.* lineages, descended from JN.1.11.1.
The analysis will become clearer as the Nextclade update has just dropped, providing accurate classification of all the new lineages. It will take me a few days to re-process the data using that update.
The lineage diagrams by Daniele Focosi are an excellent resource for making sense of the dynamic evolution picture. They currently show the "FLiRT" lineages at top-right. https://twitter.com/dfocosi/status/1775858186764861898
It seems the first wave of the JN.1.* + "FLiRT" lineages started in Nigeria (43%) during February. Note the end of that series in late February is currently the end of all available sample data from Nigeria, so JN.1.* + "FLirt" lineages are likely more dominant there by now.
The second wave was in several Asian countries in early March, notably: India (62%), Singapore and more recently Qatar (78%).
Qatar recently resumed sharing samples after a gap of several months, so presumably there was a lot of unreported growth before the samples shown here.
Across Europe, JN.1.* + "FLiRT" lineages are showing sharp growth in several countries, led by the UK (35%) and the Netherlands (reaching 31%). Recent sample sizes are often thin and patchy, which can distort the recent results.
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