Researchers Warn That New SARS-CoV-2 Sublineage NB.1.8.1 with Spike 420N and 478T Dual Substitution Spreading Globally
Nikhil Prasad Fact checked by:Thailand Medical News Team Oct 28, 2026 47 minutes ago
A new genetic form of SARS-CoV-2 is spreading rapidly across several regions, raising concerns about the virus’s continuing evolution. Researchers in Hong Kong have identified two spike protein changes, known as 420N and 478T, that appear to give descendants of the NB.1.8.1 sublineage a competitive advantage.
Hong Kong researchers identify rapidly spreading SARS-CoV-2 NB.1.8.1 descendants carrying dual spike
mutations linked to potential immune escape
The research involved institutions including the University of Hong Kong, Centre for Virology, Vaccinology and Therapeutics, Queen Mary Hospital, and University of Hong Kong-Shenzhen Hospital.
Hong Kong Sequencing Reveals Rapid Variant Expansion
Scientists analyzed 772 respiratory samples collected between January 2025 and July 2026, successfully sequencing 615 viral genomes.
Between April 19 and July 6, 2026, NB.1.8.1 descendants represented 95.6% of 113 successfully sequenced samples. Among these, 81.5% belonged to PQ.16.1.1 or its descendants.
More importantly, 94.4% of NB.1.8.1 samples carried both spike substitutions, suggesting that the combination had become dominant.
The 420N mutation, absent during 2025, first appeared in April 2026 and reached 98% of sequenced strains by June–July.
Global Surveillance Shows Alarming Growth
This
Thailand Medical News report highlights findings from international genomic surveillance showing that the dual substitution increased from below 1% before April 2026 to 36.3% in June and 50.7% in July.
Singapore recorded 43.5% prevalence among analyzed sequences, followed by Thailand at 34.6%, Taiwan at 32.3%, and Australia at 10.2%.
Dual-substitution strains showed an estimated doubling time of 1.21 months, compared with 5.46 months for strains carrying 478T alone.
Why These Spike Mutations Matter
Both substitutions affect the spike protein’s receptor-binding domain, which helps SARS-CoV-2 attach to human cells.
Previous research suggests that D420N can weaken antibody recognition, potentially helping the virus evade certain immune defenses.
Interestingly, computational modeling indicated slightly reduced binding to the human ACE2 receptor. This suggests that stronger receptor attachment does not necessarily explain the variant’s expansion.
Genetic analysis also revealed that the combination emerged independently in several viral branches, suggesting repeated evolutionary selection.
Conclusions
The findings indicate that NB.1.8.1 descendants carrying both mutations have expanded rapidly, potentially benefiting from immune escape. However, increased disease severity has not been demonstrated, and additional laboratory and epidemiological investigations remain essential.
The study findings were published in the peer-reviewed journal: Emerging Microbes & Infections.
href="https://www.tandfonline.com/doi/full/10.1080/22221751.2026.2755643">https://www.tandfonline.com/doi/full/10.1080/22221751.2026.2755643
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