- Worrying variant formed after mutant Kent virus and Californian strain merged
- Super-mutant strain could be more infectious and more likely to dodge vaccines
- One case has been identified in California, but scientists say likely to be more
The variant, not yet named, has only been spotted once but scientists fear there are likely to be more cases.
Experts are worried because it carries mutations which appear to make it able to spread faster and also to slip past some of the immunity made from past infections or vaccines.