A new variant of COVID-19, named Stratus, is rapidly spreading across the globe, characterized by a distinctive early symptom that sets it apart from previous strains. First detected by health officials in January 2025, Stratus has been classified into two subtypes: XFG and XFG.3. By June 2025, the World Health Organization (WHO) included Stratus on its monitoring list due to its swift transmission rates.
While many COVID-19 symptoms typically align with those of other respiratory illnesses—such as fever, cough, and runny nose—Stratus exhibits an unusual early sign. The most common initial symptom is a hoarse or raspy voice, which may appear before more recognizable COVID-19 indicators. Additionally, medical professionals have reported other symptoms associated with Stratus, including sore throats, nasal congestion, digestive issues, and significant fatigue.
The variant gained traction in the United States during the summer of 2025, establishing itself as the dominant strain. Health authorities indicated that the summer surge was driven not only by Stratus but also by another variant referred to as “Nimbus.” Dr. Gareth Nye from the University of Salford noted, “In most ways, it’s almost identical. However, people with this version tend to get very sore throats and a hoarse voice, compared with the other more general symptoms like cough, temperature, and aches.”
As schools resumed for the fall, Dr. Nye observed a typical spike in illnesses, attributing this to increased close contact and often lower personal hygiene among children. He emphasized that the Stratus variant has shown an ability to partially evade the immune system, thereby reducing the effectiveness of previous vaccinations. This reality underscores the necessity for individuals to remain up-to-date with their COVID-19 vaccinations.
Stratus was first observed in Southeast Asia in January 2025 and had reached the United States by March. A significant surge occurred in May and June, with the variant being identified as the predominant strain by mid-September 2025. By the end of September, Stratus was estimated to account for approximately 85% of COVID-19 cases in the country, as identified through wastewater analysis.
Dr. Peter Chin-Hong from the University of California, San Francisco, warned that Stratus presents a wider array of symptoms compared to earlier variants. “There’s a little bit more sore throats with some people, particularly older adults who didn’t get vaccinated last year,” he explained. He cautioned that Stratus’s increased transmissibility suggests a likelihood of widespread infection, particularly with children returning to school. “A sniffle is likely going to be Covid,” he added.
While the emergence of a new COVID-19 variant may cause concern, GOV.UK reassures the public that virus mutation is a standard occurrence. The agency is actively collecting data to better understand how to combat such variants. “It’s normal for viruses to mutate and change, and as more data becomes available on these variants, we’ll have a better understanding of how they interact with our immune systems and how to optimize our protection,” the report states.
The most crucial guidance remains for those eligible to ensure they receive their vaccinations as scheduled. As health officials continue to monitor the situation, the focus remains on protecting the most vulnerable populations while allowing society to resume normal activities.