What to Know About the JN.1 Variant

While the BA.2.86 or “Pirola” variant of SARS-CoV-2 never took off in the U.S., some researchers are now eyeing its descendant, JN.1, which may be more immune-evasive.

JN.1 has yet to appear on the CDC’s variant proportions tracker, but it has started cropping up in samples in France, the U.K., and Portugal.

The CDC warned in August that since BA.2.86 had more than 30 new mutations, it could have a growth advantage over other variants. That hasn’t yet materialized, but eyes are on JN.1 because it also has a mutation in L455S, which has been problematic for monoclonal antibodies, researchers said.

Amesh Adalja, MD, of Johns Hopkins University Center for Health Security in Baltimore, told MedPage Today that these factors are worth watching, but JN.1 isn’t a cause for concern just yet.

“It’s not something that has spread very vastly or deeply,” he said. “It’s a very rare variant and an offshoot of BA.2.86, and it has those mutations that were characteristic of BA.2.86 that are somewhat immune evasive, but BA.2.86 was never really able to take off.”

At this time, there is no evidence that JN.1 is going to become a dominant variant, Adalja said: “There’s no evidence that it’s spreading widely or rapidly or posing any major concern in terms of the metrics that we’re tracking. It’s just another variant where we don’t know what its fate will be, but it’s not dominant now.”

Adalja noted that even if JN.1 did become dominant, COVID-19 vaccines will very likely still protect against severe disease. In addition, he said, antivirals such as nirmatrelvir-ritonavir (Paxlovid) are “variant agnostic” and will likely continue to be effective.

Currently, HV.1 is estimated to be the dominant variant in the U.S., accounting for about 25% of cases, according to CDC’s variant proportions tracker. It’s followed closely by EG.5, which accounts for an estimated 22% of cases.

Adalja emphasized that SARS-CoV-2 will continue to mutate and that there shouldn’t be much concern about new variants before there’s substantial information about transmission and severity of disease. Widespread population immunity is a key driver of viral evolution and will continue to produce new variants, he said.

“This is what respiratory viruses do, they continue to evolve,” he added.

Indeed, experts have previously told MedPage Today that they are taking a different approach to monitoring new variants. Shishi Luo, PhD, head of infectious diseases at the population genomics company Helix, said in an earlier interview that experts are now watching hospitalizations “[r]ather than trying to follow what the new mutations are and seeing if neutralization assays or experiments are done to investigate the functional impact of the mutation.”

Luo added that scientists treat all new variants with the same caution while monitoring them for signs of increased severity or transmission.

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