
The US Centers for Disease Control and Prevention states that the JN.1 subvariant of the coronavirus is now causing about 20% of new Covid-19 infections in this country and is the fastest growing strain of the virus.
It has already spread widely in the Northeast, where it is estimated to cause about a third of new infections.
JN.1 is derived from BA.2.86, or Pirola, a subvariant that came to the world's attention over the summer due to the large number of changes in its proteins.
Scientists feared it was so mutated that it would completely escape vaccine and antibody protection against Covid-19, possibly causing another wave of the disease, as the original Omicron variant did in 2021, CNN reports.
JN.1 has only one difference in its spike protein compared to its predecessor, but that seems to have been enough to make it a more fit and faster virus.
The CDC estimates that JN.1 prevalence more than doubled in the US between late November and mid-December. This variant seems to be getting a boost from holiday travel and declining immunity.
Variant trackers say they expect JN.1 to become the dominant coronavirus variant worldwide within weeks.
The World Health Organization called it a variant of interest on Tuesday because of its rapidly increasing spread, but noted that the additional risk to public health remains low.
Studies by researchers at Columbia University and in China suggest that there is a two-fold decrease in the ability of our antibodies to neutralize this subvariant. While this isn't a huge drop, it could portend another wave of infections on the horizon.
Several countries in Europe – including Denmark, Spain, Belgium, France and the Netherlands – have seen exponential increases in JN.1 and, with it, increases in hospitalizations. It is also growing rapidly in Australia, Asia and Canada.