Overview

This elevates the following Pango lineages as labeled clades:

• BA.4 as 22A
• BA.5 as 22B
• BA.2.12.1 as 22C

Each of these still has the parenthetical "(Omicron)" designation as these are all still considered to be the Omicron variant by the WHO.

Here, we are following updated Nextclade designation rules that call for a clade to labeled if any of the following are met:

1. A VOC or VOI is recognized by the WHO and given a Greek letter label
2. A clade reaches >20% global frequency for 2 or more months
3. A clade reaches >30% regional frequency for 2 or more months
4. A clade shows consistent >0.05 per day growth in frequency where it's circulating and has reached >5% regional frequency

with additionally (2,3,4) requiring the clade to show multiple mutations in S1 or particular mutations of known biological relevance

Evidence of each of the three clades hitting these criteria is provided below:

BA.4 as 22A

• Current view of BA.4 suggests consistent growth in Gauteng (0.09 per day) with it reaching 78% frequency on April 7, but not yet enough data in KwaZulu-Natal.
• We place BA.4 at 14% regional frequency in Africa.
• BA.4 possesses spike mutations L452R, F486V and R493Q relative to BA.1 and BA.2 and additionally posses del69/70 relative to BA2.

BA.5 as 22B

• Current view of BA.5 suggests consistent growth in Gauteng (0.07 per day) with it reaching 11% frequency on April 7 and consistent growth in KwaZulu-Natal (0.11 per day) with it reaching 56% frequency on April 7.
• We place BA.5 at 6% regional frequency in Africa.
• BA.5 possesses spike mutations L452R, F486V and R493Q relative to BA.1 and BA.2 and additionally posses del69/70 relative to BA2.

BA.2.12.1 as 22C

• Current view of BA.2.12.1 suggests consistent growth in multiple US states (generally around 0.1 per day, but CA may be faster at 0.15 and NY may be slower at 0.06). Its frequencies are greater than 20% in a number of states as of April 7.
• We place BA.2.12.1 at 6% regional frequency in North America.
• BA.2.12.1 possesses L452Q and S704L relative to BA.2.