A new variant of the SARS-CoV-2 virus, known as Nimbus or NB.1.8.1, is drawing global attention following its spread across several Asian countries. The Nimbus variant, a sub-lineage of Omicron, was designated by the World Health Organization (WHO) as a Variant of Interest (VOI) on May 23, 2025.
Epidemiologist Citra Indriani, MD, from the Faculty of Medicine, Public Health, and Nursing at Universitas Gadjah Mada (FK-KMK UGM), explained that mutations in the SARS-CoV-2 virus are normal, as is characteristic of RNA viruses.
According to her, the virus continues to evolve, much like the influenza virus.
“Currently, the Nimbus variant is dominant, but it’s not the only circulating variant. There are still others under observation,” she said on Thursday, Jul. 3, 2025.
Indriani noted that, based on global data, the NB.1.8.1 variant saw a significant rise in April, but has since begun to decline.
“So, even though it’s being described as dominant, it is not currently categorized as a variant of concern in terms of disease severity,” she explained.
WHO classifies virus variants into three main categories based on genetic characteristics and public health impact: Variant of Concern (VOC), Variant Under Monitoring (VUM), and Variant of Interest (VOI).
The Nimbus variant, Indriani said, is currently classified as a VUM due to the rise in case numbers observed in several countries.
The symptoms of Nimbus infection are generally similar to those of other upper respiratory tract infections, including coughing and a runny nose.
However, Indriani pointed out that one distinct symptom frequently reported is sharp throat pain.
Even so, she emphasized that the variant does not exhibit higher severity or fatality rates compared to earlier variants, such as Omicron or Delta.
“There is still no indication that Nimbus is more severe or more transmissible than previous variants. Transmission remains via droplets, close contact, and respiratory pathways, unchanged from what we’ve known so far,” she explained.
As with other SARS-CoV-2 variants, Indriani stated that older adults, individuals with comorbidities such as diabetes, hypertension, or cancer, and those who have not completed their vaccinations remain the most vulnerable populations.
Fatalities tend to occur among those with underlying conditions and without a history of vaccination.
Therefore, Indriani emphasized that while vaccination may not provide 100% immunity, it is crucial for reducing the severity of the disease.
With increasing international mobility, the possibility of the Nimbus variant entering Indonesia is a real concern. Indriani underscored the importance of active surveillance in healthcare facilities.
“If you experience flu-like symptoms such as a cold or cough, take a break, work from home if possible, and continue wearing a mask. Cough etiquette, handwashing, and physical distancing are essential. These are basic principles of Clean and Healthy Living Behavior (PHBS) that we must maintain,” she said.
Although the Nimbus variant is a natural part of the virus’s evolution, Indriani urged the public to remain calm yet vigilant by practicing health protocols, maintaining immunity, and completing vaccination, particularly for at-risk groups.
“Public and institutional participation in surveillance, reporting, and education is crucial to prevent widespread transmission and to safeguard public health stability,” she concluded.
Author: Lintang Andwyna
Editor: Gusti Grehenson
Illustration: Freepik