Editorial: COVID-19 Six Years on and Endemic Omicron Variants of SARS-CoV-2 Under Monitoring Now Include NB.1.8.1 (Nimbus) and XFG (Stratus)

Six years ago, in December 2019, patients in Hubei Province, China, reported symptoms of atypical pneumonia that were unresponsive to treatment, and in Wuhan, an outbreak of similar cases was reported to the World Health Organization (WHO). On January 30, 2020, the WHO declared that COVID-19, caused by SARS-CoV-2, was a public health emergency of international concern (PHEIC). By November 2, 2025, the total number of COVID-19 cases reported to the WHO since 2020 was 778,900,250. On June 25, 2025, the WHO Technical Advisory Group on Virus Evolution (TAG-VE) reported a risk evaluation for two SARS-CoV-2 Omicron variants under monitoring (VUM), NB.1.8.1 (Nimbus) and XFG (Stratus). At the end of 2025, genomic analysis of the infecting SARS‑CoV‑2 virus identified them as the most common circulating viruses causing COVID-19. This editorial aims to highlight that, six years on from the initial reports of SARS-CoV-2 cases that led to the COVID-19 pandemic, complacency in infection control and surveillance has resulted in a concerning increase in infection from endemic Omicron variants, including NB.1.8.1 (Nimbus) and XFG (Stratus).