Immune Systems Advisor

The Stratus variant, scientifically designated as XFG, is a sublineage of the Omicron family of SARS-CoV-2 (the virus causing COVID-19). The XFG strain is a hybrid of two other Omicron sub variants: LF.7 and LP.8.1.2. For the four-week period ending December 20, 2025 ( CDC.gov ), the dominant variant nationwide is XFG, with 61% of cases, followed by XFG.14.1, with 15% of cases, and XFG.1, with 5% of cases. Currently subvariants of omicron are circulating, including XFV, NW.1 and XFZ." It was first detected in Southeast Asia in January 2025 and classified by the World Health Organization (WHO) as a Variant Under Monitoring (VUM) on June 25, 2025. XFG is characterized by specific genetic mutations, including JF1 + S:T22N, S:S31P, S:R190S, S:R346T, S:K444R, S:V445R, S:F456L, S:N487D, S:Q493E, and S:T572I, which contribute to its increased transmissibility compared to some prior Omicron subvariants. As of late 2025, WHO assessments consistently rate the global public health risk from ...

Overview A new COVID-19 variant, identified as NB.1.8.1, has recently emerged and is drawing international attention due to its increasing prevalence, particularly in China, and its detection in the United States and other countries. December 2025 Update: The Stratus Variant (XFG): Symptoms, Global Spread, and Impact in Late 2025 1. Emergence and Spread of NB.1.8.1 Origin and Detection: NB.1.8.1 was first identified as a significant driver of rising COVID-19 cases in China. The U.S. Centers for Disease Control and Prevention (CDC) confirmed its presence in the United States, though as of late May 2025, fewer than 20 cases had been reported domestically. Global Spread: The World Health Organization (WHO) and multiple health authorities have noted that NB.1.8.1 is now spreading worldwide, with cases reported in several countries. Its rapid dissemination has raised concerns about potential increases in COVID-19 cases in various regions. 2. Variant Characteristics Genetic Profile: NB.1.8.1...

Coronavirus cases are rising across the United States, as they have every summer since the pandemic began five years ago. Infections are growing or “likely growing” in 26 states and D.C., according to the Centers for Disease Control and Prevention, based on emergency department visit data as of July 15. A recent CDC report also notes that more laboratory tests are returning positive for the coronavirus, and emergency room visits for covid are increasing for young children. WastewaterSCAN, which tracks viruses in wastewater to monitor infectious diseases, reports that national levels of coronavirus are in the  high  category and slowly  trending upward  since early- to mid-June. The coronavirus “is still out there, it is still going through communities across the country,” said  Amanda Bidwell , scientific program manager at WastewaterSCAN. Concentrations of the coronavirus in its wastewater samples are up 38 percent in July compared with June, first rising in...