Omicron Subvariant JN.1

December 25, 2023

Researchers at the University of Tokyo predict that the omicron subvariant JN.1 (BA.2.86.1.1) is poised to become the dominant lineage of the SARS-CoV-2 virus worldwide. This variant, distinguished by a spike protein mutation known as L455S or “FLip,” was designated a variant of interest (VOI) on December 18, 2023, following a rapid surge.

Evolution from BA.2.86 and “FLip” Mutations

JN.1 is a descendant of the BA.2.86 lineage, which emerged in August 2023, carrying more than 30 mutations in its spike protein. Notably, the “FLip” mutations, including L455S and L455F, switch amino acid positions on the spike protein, enhancing transmissibility. JN.1 rapidly surpassed its predecessor in France, indicating its increased prevalence.

Impact on ACE2 Binding and Immunity

A single F456L or L455F substitution in the spike protein diminishes the receptor binding capacity of angiotensin-converting enzyme 2 (ACE2). ACE2 serves as an entry point for the SARS-CoV-2 virus. The study supervised by Yunlong Richard Cao reveals that variants with these mutations, like XBB.1.5+F456L and BA.2.86 + S: L455S, exhibit stronger binding to ACE2 and reduced protection against natural antibodies.

Transmissibility and Reproductive Number

The effective reproductive number (Re) of JN.1 in France, the United Kingdom, and Spain is higher than other variants (BA.2.86.1 and HK.3), indicating a growth advantage and increased transmissibility. This raises concerns about the potential for the virus to evade vaccination.

Immune Evasion and Breakthrough Infections

Comparative studies by BIOPIC suggest that JN.1 displays a significantly enhanced ability to evade immunity, particularly in cases of XBB breakthrough infections. This finding prompts questions about the effectiveness of existing vaccines against this evolving subvariant.

Global Prevalence and CDC’s Insights

The Centers for Disease Control and Prevention (CDC) in the United States anticipate JN.1 to account for 39-50% of all SARS-CoV-2 variants for the two weeks ending on December 23, 2023. The CDC notes an increase from previous projections, indicating the variant’s potential for higher transmissibility or immune evasion. However, the full extent of its impact on infections and hospitalizations remains uncertain.

Global COVID-19 Trends and Caution

Globally, between November 20, 2023, and December 17, 2023, there has been a 52% increase in new cases and an 8% decrease in deaths. In India, 3,241 new cases and 21 deaths were recorded during the same period. The Southeast Asia Region reported a staggering 388% increase in new cases. However, caution is advised in interpreting reported cases, given the reduction in testing and reporting.

« Previous Post Next Post »