https://www.mercurynews.com/2022/01/25/stealth-omicron-sub-variant-found-in-santa-clara-county/

Santa Clara County health officials Tuesday said they have identified two cases of a worrisome sub-lineage of the fast-spreading omicron variant of the virus that causes COVID-19 that has rapidly overtaken the most common version in other parts of the world.

Health officials had little information Tuesday about two cases of the sub-lineage, known as BA.2, and said it’s not yet known whether it is more transmissible or virulent than the dominant omicron sub-lineage, known as BA.1.