As the world continues to adapt to the evolving presence of COVID-19, health authorities are closely monitoring the rise of a new Omicron subvariant: NB.1.8.1, also known by its informal name Nimbus. Although it is not currently classified as a variant of concern, its rapid global spread and distinct symptom profile warrant attention from both the medical community and the public.
A Quietly Spreading Variant
NB.1.8.1 was first detected in early 2025 and has since shown a steady increase in cases in countries including the United States, India, China, and several countries in Europe and Latin America. According to recent data, the subvariant now accounts for around 10–11% of new COVID cases globally, up from just 2.5% a month ago.
Virologists and epidemiologists note that NB.1.8.1 is not necessarily more dangerous in terms of disease severity, but it does appear to spread efficiently. This has led the World Health Organization to label it a “variant under monitoring,” particularly due to its growing share of sequenced cases.
Recognizing the Symptoms
The symptoms associated with NB.1.8.1 are largely in line with previous Omicron subvariants: an elevated body temperature, fatigue, nasal congestion, coughing, and muscle aches. However, what sets Nimbus apart is the frequency and intensity of sore throats reported by patients. Descriptions such as “razor-blade sore throat” have surfaced in multiple countries, pointing to a symptom that is particularly severe and sometimes the earliest sign of infection.
In some cases, patients also report low-grade fever, mild chills, or gastrointestinal issues such as nausea and diarrhea. Given that symptoms can present mildly or be mistaken for seasonal colds or allergies, health professionals emphasize the importance of early detection and symptom tracking.
Why Monitoring Body Temperature Is Important
One of the key indicators of a viral infection, including COVID-19, is an elevated body temperature. Even a mild fever can be the first physiological sign that the immune system is responding to an infection—before other symptoms become apparent.
With variants like NB.1.8.1, which may present with non-specific or gradually developing symptoms, monitoring body temperature on a regular basis provides a valuable early warning system. Twice-daily temperature checks, in the morning and evening, can help individuals spot subtle changes that might otherwise go unnoticed.
Regular monitoring is especially recommended for:
- People with frequent social contact (e.g. educators, retail workers, healthcare staff)
- Households with immunocompromised members
- Parents with young children in school or daycare
- Individuals recently returned from international travel
- Those living in areas where NB.1.8.1 is rising in prevalence
A Practical Tool for Preventive Awareness
In a period where most countries are no longer conducting mass testing and where many cases go unreported, home-based health vigilance plays a crucial role. Keeping track of one’s temperature doesn’t replace a COVID test, but it can be a simple and useful step toward timely action.
If a rise in temperature is detected, even without other symptoms, individuals may consider isolating, wearing a mask, avoiding close contact with vulnerable people, or seeking medical advice. In this way, temperature checks serve not only personal health but broader public health efforts as well.
As the NB.1.8.1 subvariant becomes more widespread, staying informed and aware of subtle health changes is increasingly important. While this new strain does not appear to cause more severe illness, its rapid transmission and unusual symptom profile underline the value of early detection. Regular temperature monitoring—ideally twice per day—can help individuals catch the first signs of infection, make informed decisions, and limit the potential spread to others.
Source,
Exergen P/N 850467