CDC Identifies New Sub-Variant JN.1 of Omicron

November 13, 2023

The Centers for Disease Control and Prevention (CDC) in the United States have reported the emergence of a new sub-variant of the Omicron variant, known as JN.1, with limited information available about its characteristics and potential impact.

Discovery of Sub-Variant JN.1

The CDC flagged the presence of the new sub-variant, JN.1, which is derived from the Omicron variant BA.2.86. This discovery has raised concerns but has not yet been fully characterized.

Geographic Spread

JN.1 has been detected in 11 countries, including the United Kingdom, Iceland, Portugal, Spain, and the Netherlands. Its first identification was in the United States in September 2023. However, it currently represents a minor portion of SARS-CoV-2 viruses in the US, making up only 0.1 percent, while the majority belong to the XBB group of the Omicron variant.

Key Mutations and Immunity

Unlike its ancestor, which had over 30 mutations, JN.1 carries an additional spike mutation known as L455S. This mutation is suspected to have the potential to evade immunity. Specifically, it primarily escapes Class 1 neutralizing antibodies.

Uncertainty Surrounding Spread

While JN.1’s predecessor, BA.2.86, did not spread efficiently, experts believe it’s uncertain whether the new sub-variant JN.1 will gain prominence. It is currently under close observation to assess its transmissibility and impact on immunity.

Other Notable Variants

Prior to JN.1’s emergence, the US saw the dominance of HV.1, a derivative of EG.5, which accounted for a significant portion of infections. Researchers suspect that HV.1’s enhanced transmissibility and immune evasion might be linked to specific mutations.

Vaccine Efficacy

The effectiveness of existing vaccines against HV.1 remains uncertain. Experts believe that the vaccines may perform similarly against both HV.1 and EG.5. However, more data is needed to confirm this.

Ongoing Monitoring

The CDC and the World Health Organization (WHO) continue to monitor the evolving landscape of COVID-19 variants. New variants are expected to emerge, some of which may replace previous ones.

Global Impact

Hospitalization rates due to COVID-19 continue to fluctuate globally, with several countries reporting high numbers in recent months. The reduction in testing and reporting has made it challenging to accurately assess infection rates.

WHO’s Surveillance

The WHO is closely monitoring several variants of interest, including XBB.1.5, XBB.1.16, and EG.5, along with six other variants under surveillance. EG.5 remains predominant, representing a significant portion of global sequences.

Continual Monitoring

As countries integrate COVID-19 reporting into respiratory disease surveillance, the WHO plans to continue monitoring data related to morbidity and its impact on health systems.

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