New COVID-19 Variant NB.1.8.1: Symptoms, Spread and The Latest Combination Therapies for Vulnerable and Immunocompromised Persons: A Literature Review and Clinical Experience in June 2025

Despite the end of the pandemic, COVID-19 continues to pose a serious health threat. As of May 2025, the most notable COVID-19 variant is NB.1.8.1, informally known as “Nimbus.” This Omicron subvariant has been rapidly spreading across Asia, Europe and North America. It has been linked to a particularly severe sore throat, described by patients as feeling like “razor blades,” along with other flu-like symptoms such as fatigue, cough, fever, congestion and muscle aches. The World Health Organization (WHO) has designated NB.1.8.1 as a “Variant Under Monitoring” due to its increased immune evasion capabilities. Despite its rapid transmission, current data suggest that it does not lead to more severe disease compared to earlier strains. In addition to NB.1.8.1, other Omicron subvariants such as XEC and LP.8.1 continue to circulate. XEC, a recombinant variant fiint identified in Germany in June 2024, has been increasing in prevalence globally. It has been detected in several countries, including South Africa and is currently the most common SARS-CoV-2 subvariant reported. Health authorities continue to monitor these variants closely. Preventive measures such as vaccination, mask-wearing and good hygiene remain essential in reducing the spread of COVID-19. The challenges of outpatient administration and associated costs, monoclonal antibodies were a mainstay of the COVID-19 armamentarium from November 2020, when bamlanivimab first received US Food and Drug Administration Emergency Use Authorization (EUA), through November 2022. Ideal qualities of treatments include effectiveness in preventing hospitalization and death, safety and tolerability for patients, easy administration in the outpatient environment and cost-effectiveness. Monoclonal antibodies (mAbs) that neutralize SARS-CoV-2 fit the safety and efficacy profile in randomized clinical trials. This minireview of clinical experience explain the latest variant of concerns, the symptoms and the importance of early combination therapies for NB 1.8.1 to treat quickly immunocompromised and elderly persons.