# RKS: NB.1.8.1 - The VUM Becoming A VOC?

    

# RKS: NB.1.8.1

THE VUM BECOMING A VOC?

RKS / 2025-2026 / Ser 8 / Blog 4

1st January 2026

THE NEW EMERGENT SARS-CoV-2 VARIANTS

ALL ABOUT OMICRON SUBTYPES

Dear Reader,

SARS-CoV-2 is the coronavirus responsible for the COVID-19 pandemic, causing a contagious disease called Coronavirus disease 2019 (COVID-19). The variants that emerged in 1920 were alpha (B.1 subtypes - United Kingdom first), beta (B.1 subtypes - South Africa first), gamma (P.1 - Brazil first) and delta (B.1 subtypes - India first). The omicron variant of SARS-CoV-2 emerged in 2021 (South Africa first) onwards. Of the latter, the current two of looming concerns include LP.8.1 and NB.1.8.1 which are not only a global scare but also assuming alarming proportions in India. 

SARS-CoV-2 VARIANT CLASSIFICATION

Variant classification serves as an important communication tool for alerting countries about the emergence of SARS-CoV-2 variants with concerning properties likely to impact the population. The European Centre for Disease Prevention and Control (ECDC) as well as the World Health Organization (WHO) has segregated the new variants under the following assigned categories:

1. Variant under monitoring (VUM) - SARS-CoV-2 variants that scientists are keeping an eye on but are not yet considered a major threat. 
2. Variant of interest (VOI) - SARS-CoV-2 variants that are closely monitored for potential risks.
3. Variant of concern (VOC) - SARS-CoV-2 variants that spread easily and may affect immunity.

The classification is based on transmissibility, immunity and severity of infection.

VUM & VOI

Omicron viruses are classified into several sublineages, including BA.1, BA.2 and BA.3, which have been observed worldwide. In the early period after Omicron's emergence, BA.1 was the dominant sublineage; however, in Denmark, the United Kingdom (UK), India, the Philippines and South Africa, BA.2 became dominant and the latter being reported to be more transmissible than BA.1 subvariants. The prevalence of BA.3 has remained low.

BA.4 and BA.5 took over BA.2 and has become the new dominant SARS-CoV-2 variant. It started the fifth COVID-19 wave in South Africa (2022) and these variants were 36% more infectious than BA.2. The XEC subvariant is a recombinant virus derived from merging of two known Omicron lineages: JN.1:KP.3.3 and KS.1.1 (subvariant of BA.2.86).

Table: As per WHO there are currently 5 variants either under monitoring (VOM) or of interest (VOI).

Omicron did not evolve from any other variant, but instead diverged on a distinct track, perhaps in 2020. Omicron was first detected in November 2021 in laboratories in Botswana and South Africa and by 2022 it had spread to 149 countries. Although Omicron multiplies around 70 times faster than the delta variant in the bronchi (lung airways) the evidence suggests it is less severe than the previous variants, especially when compared to even the deadly delta SARS-CoV-2, since it might be less able to penetrate deep lung tissue.

Along with BA.2, the latest BA.4 and BA.5 to enter the fray are all Omicron variants.

VOC

The VUM - LP.8.1 and NB.1.8.1 are fast becoming concerning SARS-CoV-2 viruses.  LB.8.1 is the dominant variant that is starting to decline whilst NB.1.8.1's proportions are increasing globally.

LP.8.1

LP.8.1 caused large waves of COVID infections around the world in late 2023 and early 2024. It was first detected only in July 2024 and now has been confirmed to spread across 23 countries. LP.8.1 has been responsible for 60% of COVID cases in UK, 55% in United States of America (USA) and 20% in Australia. Specifically, a publication has reported on June 5, 2025, that India had reported 5754 active RT-PCR positive cases of LP.8.1, primarily in Delhi, Kerala, Maharashtra and Tamil Nadu. 73% of COVID cases in India have been attributed to LP.8.1 but the WHO notes that LP.8.1 circulation is decreasing.

NB.1.8.1

NB.1.8.1 is a “recombinant” variant, which means it has arisen from the genetic mixing of two or more existing variants. This NB.1.8.1 variant was first identified in January 2025 and has rapidly spread across Asia and into other regions, including parts of USA. According to WHO, as of May 18, 2025, the NB.1.8.1 variant has been identified in 22 countries, accounting for 10.7% of global SARS-CoV-2 incidences. 

As of June 4, 2025, India reported 4,302 active COVID-19 infections. States such as Delhi, Uttar Pradesh, West Bengal, Gujarat and especially Kerala have experienced a steady rise in cases. In fact, there has been a steady rise on weekly basis resulting in setting an alarm signal to fend against NB.1.8.1 Omicron subvariant attack.

ADDRESSING NB.1.8.1 CHALLENGE

Common symptoms of the NB.1.8.1 strain include sore throat, cough, muscle aches, fever and nasal congestion. It can also cause gastrointestinal (GI) symptoms such as nausea and diarrhea. 

The "coronavirus spike" refers to the spikes of glycoprotein, a protein found on the surface of coronaviruses. These proteinaceous spikes are crucial for the virus's ability to enter (by binding with cell surface) cell and infect tissues. There are approximately 25 to 100 spike trimers per virion. Every mutation [change in DNA (deoxyribonucleic acid) sequencing] in spike protein creates a new variant of SARS-CoV-2 each time. 

Fig: Coronavirus spikes.

In comparison to the currently dominant LP.8.1, NB.1.8.1 has the following additional spike mutations: T22N, F59S, G184S, A435S, V445H and T478I. Spike mutations at position 445 have been shown to enhance binding affinity to hACE2 tissue receptors, which could increase the variant’s transmissibility and hence make it more contagious. However, there is no indication that NB.1.8.1 leads to more severe illness than other circulating variants.

Health experts worldwide opine that there is no evidence that the new strain of the coronavirus is more severe or deadly than any previous strains. The concern is that NB.1.8.1 does appear to spread more easily.

NB.1.8.1 does not show enhanced humoral immune evasion ability compared with LP.8.1. Hence, both the variants can reasonably be checked with booster doses of current SARS-CoV-2 vaccines. The recommendations for vaccination as per Global Virus Network (GVN) are as follows:

• Adults aged 65 years and older, and individuals with underlying conditions, should receive an updated COVID-19 booster tailored to circulating variants.
• All individuals 6 months and older, including children and adolescents, are encouraged to adhere with current vaccination schedules, especially ahead of the fall and winter respiratory seasons.
• Children 6 months to 17 years of age should receive an age-appropriate, updated COVID-19 vaccine dose if they have not already done so within the past year, as protection from earlier vaccines may have waned over time. Pediatric vaccination helps prevent severe outcomes, including hospitalization and multisystem inflammatory syndrome in children (MIS-C).
• Pregnant individuals are strongly encouraged to stay with current COVID-19 vaccination. Vaccination during pregnancy reduces the risk of COVID-19 hospitalization in infants by 61% and protects newborns for up to six months after birth - an especially important window given the high rate of emergency department visits for COVID-19 amongst infants. Studies have consistently demonstrated that infection during pregnancy increases the risk of preterm birth, miscarriage, fetal death and long-term neurodevelopmental issues. No safety concerns have been identified regarding vaccination in pregnancy or neonatal outcomes.

Those not receiving a COVID-19 booster in the past year should consult a healthcare provider about updated vaccine timing and eligibility.

The principal benefits of vaccination are preventing severe disease, rather than preventing infection itself.

CONCLUSIONS

More than five years since COVID was declared a pandemic, the citizens are still facing the regular emergence of new variants of the virus, SARS-CoV-2. Omicron subtypes are a distinct variety of COVID virus that has emerged since 2020 and till date there have been a total of 310 variants (Pango lineages - which utilizes the genome sequence for classifying) detected. In the case of NB.1.8.1 (an Omicron subtype) infections the general population faces a lower risk of severe illness. However, certain groups remain vulnerable like - older adults (over 75 years), the immunocompromised, and those with comorbidities like diabetes or heart disease and for whom booster vaccines are a definite must. 

The GVN network was founded in 2011 by Robert Gallo in collaboration with William Hall and Reinhard Kurth (USA), and 24 countries' virologists were members of the network as of 2015. Their recommendations imply that booster doses of vaccine can stall and stun the NA.1.8.1 variant since experts have noted that widespread immunity-built through vaccinations and prior infections - has blunted the virus’s impact, making severe outcomes rarer.

So don't fret over the new COVID surge, but staying protected safe should be the moto. This is essential when one remembers how many family members are suddenly infected and fall ill when someone from the family, or a guest who has travelled enters and stays in the house. This could have been NA.1.8.1 which is not detected since RT-PCR testing now not a norm.

DR R K SANGHAVI

Prophesied Enabler

Experience & Expertise: Clinician & Healthcare Industry Adviser

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