JN.1 Covid variant has increased transmissibility, immune escape: Study

The JN.1 variant of the SARS-CoV-2 virus not only spreads easily but also seems to resist immunity, according to a study that emphasises the urgent need for strategies to address its threat to public health.

The emergence JN.1 has sparked global concern due to its distinct genetic features and heightened infectivity. Carrying more than 30 spike protein mutations, including the hallmark Leu455Ser, JN.1 exhibits substantial potential for immune evasion.

Researchers from The University of Tokyo, Japan, used genomic surveillance data from across France, the UK, and Spain, uncovering novel findings regarding the virological properties of JN.1.

The study, published in The Lancet Infectious Diseases journal, sheds light on the variant's potential to become the dominant lineage and alerts the global health community.

The researchers found that the reproductive number of JN.1 was found to surpass that of its counterparts in the three countries studied, suggesting a potential global dominance in the near future.

Reproduction number is the expected number of cases directly generated by one case in a population where all individuals are susceptible to infection.

By the end of November 2023, JN.1 had already surpassed HK.3 variant in both France and Spain, marking a significant shift in the landscape of SARS-CoV-2 variants, the researchers said.

Of concern to public health is that JN.1 not only spreads easily but also seems to resist immunity, they said.

Initial experiments using the blood of rodents infected or vaccinated against BA.2.86 showed that those rodents demonstrated an effective neutralisation of both BA.2.86 and JN.1, which is called a cross-reactive immune response, the researchers said.

However, on comparing breakthrough infections in people where the virus overcomes immunity, JN.1 proved more challenging to neutralise than BA.2.86 variant, they said.

Particularly notable was the finding that JN.1 strongly resisted the XBB.1.5 vaccine, making it one of the most immune-evading variants discovered so far, according to the researchers.

"Our findings will help people understand the risk of the SARS-CoV-2 JN.1 variant, including its potential to cause epidemic surges around the world," said Professor Kei Sato from The University of Tokyo.

The study underscores the importance of continued vigilance in monitoring and understanding the evolving landscape of SARS-CoV-2 variants.