BREAKING! The New SARS-CoV-2 Variant, NB.1.8.1 is The Most Dangerous So Far and Poses a Major Threat!
Nikhil Prasad Fact checked by:Thailand Medical News Team May 02, 2025 22 hours, 17 minutes ago
Medical News:
Study of New SARS-CoV-2 Variants BA.3.2, XFH, XFG, NB.1.8.1, XEC.25.1 and LF.7.9 Indicates That NB.1.8.1 is a Major Threat!
A new wave of SARS-CoV-2 variants is now under close scrutiny as scientists from Peking University, Tsinghua University, and Changping Laboratory in Beijing, China, have revealed alarming findings about several recently emerged strains, especially NB.1.8.1. Their detailed investigation compared six new SARS-CoV-2 variants—BA.3.2, NB.1.8.1, XFH, XFG, XEC.2.5.1 and LF.7.9—and found that NB.1.8.1 presents a particularly dangerous mix of immune evasion and infectivity that could make it a significant threat in coming months.
The New SARS-CoV-2 Variant, NB.1.8.1 is The Most Dangerous So Far and Poses a Major Threat
This
Medical News report dives into how this particular variant stands apart from the rest, and what it means for the future of the pandemic.
Understanding the New Variants
The variant BA.3.2 is a heavily mutated version of the BA.3 lineage and carries over 50 changes to its genetic code, raising fears it might behave like the BA.2.86 (JN.1) variant, which caused significant waves of infection. However, despite its alarming mutation count and strong ability to evade immune responses, BA.3.2 suffers from poor infectivity due to its spike protein adopting a “closed” structure, making it difficult to bind effectively to human cells.
On the other hand, NB.1.8.1, along with other variants like XFG and LF.7.9, seems to be evolving more efficiently. These newer variants are showing what scientists call “growth advantages” over the currently dominant strain LP.8.1.1. That means they are spreading more easily and outcompeting older variants.
NB.1.8.1 Stands Out for All the Wrong Reasons
NB.1.8.1 emerged as a descendant of the XDV.1.5.1 sub-lineage and contains mutations such as Q493E, A435S, and K478I. What makes it especially worrying is that it maintains a high binding affinity to the human ACE2 receptor, which is the gateway the virus uses to enter cells. Unlike BA.3.2, it has no trouble attaching to and infecting human cells. At the same time, it has developed ways to evade the body’s immune defenses, including antibodies produced by prior infection or vaccination.
Tests done using pseudoviruses (harmless versions of the virus used for lab studies) confirmed that NB.1.8.1 was one of the most infective and evasive strains tested. While BA.3.2 resisted antibodies, it couldn’t infect cells well. NB.1.8.1, however, strikes a dangerous balance—avoiding immune detection while still spreading efficiently.
Other Variants Show Mixed Threat Levels
LF.7.9 and XFG also carry significant mutations that help them escape the immune system. However, their ability to bind to ACE2 is weaker due to specific mutations like A475V and N487D. These changes reduce their capacity to infect human cells unless they ac
quire further adaptive mutations to fix this.
XFH, another fast-spreading recombinant variant, similarly struggles with ACE2 binding, partly due to a unique L335S mutation.
Despite their weaknesses in infectivity, all these variants—including XFG, XFH, and LF.7.9—show stronger immune escape properties compared to LP.8.1.1. That means even if they aren’t spreading as well yet, they could evolve further and become more dangerous.
The Testing Methods Used
The scientists used multiple laboratory techniques to assess the threats posed by these variants. These included:
-ACE2-binding assays: Measuring how well the virus spike proteins attach to the human ACE2 receptor.
-Pseudovirus infectivity tests: Gauging how efficiently the virus can infect human cells in controlled environments.
-Neutralization tests: Using blood plasma from vaccinated and previously infected people to see how well antibodies can stop the new variants.
They tested plasma from people who had breakthrough infections with previous Omicron strains (like BA.5 and JN.1) after vaccination. NB.1.8.1 showed significant resistance to neutralizing antibodies in these samples—1.5 to 1.6 times lower neutralizing titers compared to LP.8.1.1.
Why NB.1.8.1 Could Become the Next Dominant Variant
The biggest concern is that NB.1.8.1 has found a “sweet spot” where it can both avoid immune responses and still infect human cells efficiently. While BA.3.2 was a surprise due to its massive number of mutations, its closed spike protein conformation made it far less infectious.
NB.1.8.1, by contrast, has no such limitation. It not only has a strong receptor binding domain (RBD) that remains "open" for infection but also carries mutations that reduce the power of neutralizing antibodies, especially those that target Class 1 and Class 2 antibody sites. It also resists Class 4 antibodies, which are important in people vaccinated with inactivated virus vaccines—commonly used in many Asian countries.
Key Findings About Immune Escape and Antibody Resistance
-BA.3.2: Strongest antibody evasion, especially from Class 1/4 antibodies, but lowest ACE2 binding and infectivity.
-NB.1.8.1: Moderate antibody evasion, but highest ACE2 binding and strong infectivity, making it a serious contender to become dominant.
-LF.7.9 and XFG: Moderate to strong antibody resistance, but poor ACE2 binding.
-XFH: Poor ACE2 binding and less pronounced immune escape.
-XEC.25.1: Reasonably balanced, but not as dangerous as NB.1.8.1.
Conclusion and Public Health Implications
The emergence of NB.1.8.1 marks a potentially dangerous new phase in the ongoing evolution of SARS-CoV-2. Unlike variants that are either good at infecting or good at hiding from the immune system—but not both—NB.1.8.1 appears to excel at both. This makes it a serious threat for future outbreaks. Public health agencies must continue monitoring its spread, and vaccine makers may need to consider updating their formulas to stay ahead.
While BA.3.2 looks terrifying on paper due to its sheer number of mutations, its poor infectivity means it is unlikely to pose a serious risk unless it mutates further to improve its receptor binding. The same goes for XFG and LF.7.9—they have the potential to become more dangerous but will need additional mutations to do so.
NB.1.8.1, however, is already well-equipped. It has the right mutations for high infectivity and immune escape, making it highly likely to dominate future transmission waves if left unchecked. This highlights the importance of global genomic surveillance and rapid scientific assessment of emerging variants, particularly in regions where immunity from previous infections or vaccinations may not offer strong protection.
The study findings were published on a preprint server and are currently being peer reviewed.
https://www.biorxiv.org/content/10.1101/2025.04.30.651462v1
Thailand
Medical News would like add that while this study did not cover the fusogenic capabilities of the new NB.1.8.1 variant and also the other receptors that it can bind to and its tropism to various human cell types, preliminary data from another current study being conducted by German, British and American researchers whose findings will be published on a preprint server in coming weeks indicates that the NB.1.8.1 variant has enhanced fusogenic properties and is far worse than Delta, and it uses not only the ACE2 receptors and other receptors that have been found to be used by the SARS-CoV-2 virus but also newer receptors such as various sialic acids and gangliosides, laminin, nectin-1, and heparan sulfate proteoglycans.
For the latest on the new SARS-CoV-2 Variants, keep on logging to Thailand
Medical News.
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