New Delhi, 27 May 2025: As the world steps cautiously into the post-pandemic era, new COVID-19 variants continue to emerge, reminding us that the virus is far from over. One such variant—NB.1.8.1—has recently been designated as a Variant Under Monitoring (VUM) by the World Health Organization (WHO). This classification has prompted increased global attention, though experts are urging the public not to panic but remain alert.
In India, as of May 2025, NB.1.8.1 has been detected in several states and is being closely tracked for its behaviour, symptoms, and transmission rate. Here’s what we currently know about this newly flagged variant and how it differs from its infamous predecessors like Delta and Omicron.
What is NB.1.8.1 and Why is it a Variant Under Monitoring (VUM)?
A Variant Under Monitoring (VUM) is a classification used by the WHO for SARS-CoV-2 variants that show early signs of genetic changes which could potentially affect virus characteristics such as transmissibility, immune escape, or disease severity. However, evidence is still insufficient for it to be categorized as a Variant of Interest (VOI) or Variant of Concern (VOC).
NB.1.8.1, first detected in early 2025, is a sub-lineage of the Omicron family and carries several mutations in the spike protein, particularly in regions that are critical for immune system recognition. While no drastic changes in severity have been noted so far, the variant’s genetic profile has raised red flags due to its potential to spread efficiently and evade partial immunity.
How Severe Is NB.1.8.1 Compared to Delta or Omicron?
So far, NB.1.8.1 has shown milder clinical symptoms, similar to the later Omicron subvariants, which mainly caused upper respiratory infections rather than severe lung complications. According to recent updates from the WHO and Indian Council of Medical Research (ICMR), most cases have been mild to moderate, with symptoms resolving within 5–7 days.
Unlike the Delta variant, which caused severe pneumonia and high hospitalization rates during India’s second wave in 2021, NB.1.8.1 doesn’t seem to cause major respiratory complications. However, some doctors have raised concerns about the variant’s impact on the elderly and immunocompromised, especially those with comorbidities.
In states like Maharashtra, Karnataka, Kerala, and Rajasthan, a total of 11 deaths have been reported in recent weeks in individuals who tested positive for NB.1.8.1. Health experts emphasize that most of these fatalities involved underlying health issues such as diabetes, cancer, or cardiovascular disease. Still, public health agencies are not taking the variant lightly.
Common Symptoms of NB.1.8.1
Infected individuals have reported flu-like symptoms which are similar to other Omicron subvariants. According to reports from clinicians across India, current symptoms of NB.1.8.1 in 2025 include:
Sore throat
Fatigue or tiredness
Low-grade fever
Mild cough
Headache
Nasal congestion
Muscle aches
Nausea or vomiting
Diarrhoea or other gastrointestinal disturbances
Unlike the Delta variant, loss of smell or taste has not been widely reported with NB.1.8.1. Also, shortness of breath and low oxygen levels—which once marked severe COVID-19 cases—are rarely seen in current infections.
Medical professionals advise that if symptoms persist beyond 3–4 days, individuals should undergo a rapid antigen home test or an RT-PCR to confirm infection and begin isolation.
How Fast Is NB.1.8.1 Spreading?
Although classified as a Variant Under Monitoring, NB.1.8.1 has exhibited signs of enhanced transmissibility. According to the Indian SARS-CoV-2 Genomics Consortium (INSACOG), the variant’s genome contains spike mutations that may aid in quicker cell entry and mild immune escape, meaning it can potentially infect even those who’ve had previous COVID-19 infections or vaccinations.
Currently, there are 1,047 active cases linked to NB.1.8.1 in India. Though the numbers may seem modest, public health authorities fear an undercount due to a decline in routine testing and reporting. Some experts suggest that actual infections could be significantly higher.
The WHO has not yet classified NB.1.8.1 as a VOI or VOC, but continued mutations in the spike protein could potentially increase its risk profile in the coming months if transmission escalates.
Is There a Need to Worry?
While panic is unwarranted, health authorities recommend caution and preventive measures—especially for high-risk individuals. WHO and ICMR have reinforced basic health protocols:
- Wearing masks in crowded places
- Maintaining hand hygiene
- Staying updated on booster vaccinations
- Avoiding unnecessary travel if symptomatic
Experts also warn against complacency, especially with large gatherings returning across India. “We have seen how quickly variants can take over when conditions are right,” said Dr. Anupama Mehta, a virologist based in Delhi. “We must remain vigilant, particularly in the coming monsoon months when respiratory illnesses are more common.”
The emergence of NB.1.8.1 is a stark reminder that COVID-19 continues to evolve. Although current data does not indicate a major threat like previous deadly waves, the variant’s presence underscores the need for continued surveillance, testing, and public health readiness.
As India and the world move forward, adapting to a ‘new normal’ will require remaining alert to subtle changes in virus behaviour. Health experts emphasize that with prompt diagnosis, timely care, and cautious behaviour, the threat from variants like NB.1.8.1 can be managed effectively without disrupting life.
