Understanding the Impact of the XBB.1.16 Lineage

• The XBB.1.16 variant has already been identified in approximately 14 countries worldwide, with the first sequence of this lineage traced back to a viral genome detected in New York.
• Originating from the XBB lineage, the XBB.1.16 lineage is a recombinant lineage of the SARS-COV2 virus.
• The XBB.1.16 lineage carries several mutations . Preliminary data indicates that this variant may have a competitive advantage over other SARS-CoV-2 lineages, including the XBB.1.5 lineage.
• Amidst a surge in seasonal influenza H3N2 cases, a spike in COVID-19 cases was observed in March 2023, despite a relatively low number of tests conducted.
• The total number of cases in India has reached 6000, with the XBB.1.16 lineage believed to be a major contributing factor to this surge.
• Genomic surveillance data suggests that XBB.1.16 accounts for over 30% of all sequenced genomes in March 2023, with its share of infections on the rise.
• Initial findings suggest that while there is no significant difference in clinical severity between XBB.1.16 and other Omicron variants, there may be a higher risk of reinfection with XBB.1.16 due to its rapid propagation ability.
• Therefore, it is crucial to closely monitor the spread of the XBB.1.16 lineage, especially if the number of Covid-19 cases continues to rise.

The Evolution of SARS-CoV-2

• SARS-CoV-2 has undergone significant evolution since the onset of the pandemic in 2020, with multiple waves of infection observed across India.
• Recombinant or Chimeric genomes evolve through the co-infection of multiple variants, resulting in recombination between genomes.
• Although most recombinations do not yield powerful variants, it is crucial to monitor such variants as there is a risk that a rare variant may result in a new lineage with greater functional capabilities than its parent lineages.
• Throughout the Covid-19 pandemic, numerous variants have been identified and named by the PANGO network, an international consortium of researchers dedicated to naming variants of SARS-COV2 lineages. The PANGO network has developed a system for identifying and designating SARS-COV2 recombinants and has to date identified and designated approximately 100 recombinant lineages, denoted by the letter ‘X’ followed by a letter indicating the order of detection.