Understanding the New COVID Variant NB.1.8.1 Spreading Heavily in Singapore: Severity and Prevention

COVID cases in Singapore surged past 10,000 in May 2026. Here is an in-depth look at the new COVID variant NB.1.8.1 and its key symptoms."A sore throat like being cut by a razor blade"Vaccines remain essential, experts confirm.

Watch closely: Singapore's new COVID wave caused by variant NB.1.8.1, with a key symptom of a sore throat like a razor blade cut.

This has become a major concern for health-conscious individuals and travelers, as COVID-19 in Singapore regained attention in mid-May 2026. Cases jumped sharply by 12,700 within one week, up nearly 60% from the previous week.

We will explore what this new spreading COVID variant is, its symptoms, and how to prepare safely.

Getting to know the new COVID variant NB.1.8.1, also known as"Nimbus"What is it?

According to Singapore's Ministry of Health and related agencies, the main variant currently accounting for over half of infections is the subvariant NB.1.8.1 (also called Nimbus). This virus is an Omicron subvariant derived from the recombinant strain XDV.1.5.1 and is linked to the JN.1 lineage.

• Strong cell attachment enables fast spread: This variant has mutations in its spike protein that allow it to bind strongly to human cell receptors (ACE2), enhancing its ability to spread quickly and widely, with slight immune evasion.

Latest COVID symptoms: Clear check on the razor-blade sore throat

Medical reports show that most NB.1.8.1 infections cause mild illness, but the most distinctive and frequently reported symptom is as follows.

• Severe sore throat (Razor-blade throat): Patients experience intense, sharp throat pain resembling a cut from a razor blade.
• Other accompanying symptoms: Fatigue, fever, mild or dry cough, muscle aches, and nasal congestion or runny nose.
• Symptoms that have decreased: Loss of taste and smell, common in previous variants, is much less frequent with this variant.

Global health agencies like the WHO and South Africa's NICD have assessed and confirmed there is currently no clinical evidence indicating NB.1.8.1 causes new or more severe symptoms compared to earlier variants. ICU admissions remain very low, averaging only one case per day in Singapore.

Why has Singapore experienced a new COVID wave?

Singapore's Ministry of Health and experts explain that this wave results from several combined factors:

• Declining immunity: Population immunity from vaccination or prior infection wanes over time.
• A new, more infectious variant: The emergence of NB.1.8.1, which efficiently infects cells and spreads rapidly.
• Social behavior: Increased social gatherings, travel, and the endemic nature of respiratory viruses cause periodic waves throughout the year.

Are vaccines still necessary? Prevention tips for health-conscious individuals

Doctors and experts respond that vaccination remains"Necessary and effective"Current COVID-19 vaccines (including those updated for variants JN.1, KP.2, or LP.8.1) continue to produce antibodies against NB.1.8.1, preventing severe illness and reducing hospitalization risk. Singapore's Communicable Diseases Agency recommends booster shots at least once a year for at-risk groups such as people over 60, pregnant women, and those with chronic conditions.

Basic self-care measures

• Maintain personal hygiene: Regularly wash hands with soap and cover mouth/nose when coughing or sneezing.
• Wear masks: Put on a mask immediately when respiratory symptoms begin or when entering crowded public places.
• Isolate when sick: Reduce social interactions and avoid unnecessary travel when unwell to prevent spreading the virus.
• Improve air quality: Open windows for ventilation or use HEPA-filter air purifiers in enclosed spaces.

Although the NB.1.8.1 variant spreads faster due to natural mutations, it is not more severe. For health-conscious people and Thai travelers, maintaining basic hygiene and following vaccination recommendations remain the best protection for safely living with this endemic disease.