New COVID-19 Variant “Stratus” (XFG): A Focus on Hoarseness and Sore Throat

The World Health Organization (WHO) has added the COVID-19 variant XFG, informally known as “Stratus,” to its monitoring list. While the overall public health risk remains low, Stratus is notable for its high prevalence of hoarseness, a less common symptom in previous variants. The variant combines elements of the LF.7 and LP.8.1.2 lineages, exhibiting mutations that enhance its ability to evade immune defenses.

Stratus’s Emergence and Global Spread

Stratus (XFG) has rapidly spread across the northern hemisphere, becoming the dominant variant in several regions. Its emergence marks a significant shift in the circulating SARS-CoV-2 variants. Initially dominant in India during the spring, Stratus’s global spread is evident in data from GISAID, which shows a substantial increase in its prevalence from 7.4% to 22.7% of submitted samples within a month.

The rapid spread underscores the ongoing adaptability of the SARS-CoV-2 virus and the need for continued surveillance.

The WHO’s designation of Stratus as a “variant under monitoring” highlights the importance of tracking its evolution and impact.

Key Symptoms and Clinical Presentation

While Stratus doesn’t appear to cause more severe illness or increased mortality compared to other circulating variants, a distinctive symptom is its high prevalence of hoarseness (laryngitis). This symptom, less common in previous variants, is accompanied by other typical COVID-19 symptoms such as dry cough, sore throat, fever, muscle aches, and fatigue.

The characteristic hoarseness is a key feature distinguishing Stratus from other variants.

The combination of hoarseness and other respiratory symptoms makes Stratus difficult to distinguish clinically from other respiratory illnesses like the flu, RSV, and strep throat.

Vaccine Effectiveness and Future Outlook

Currently approved COVID-19 vaccines are expected to remain effective against Stratus, offering protection against symptomatic and severe disease. However, laboratory tests have shown a roughly two-fold reduction in antibody effectiveness compared to the globally dominant variant at the time of the study. The WHO will continue monitoring the variant’s impact on vaccine efficacy to inform potential vaccine updates.

The mutations in Stratus’s spike protein contribute to its ability to evade immune defenses.

Continued monitoring is necessary to assess the long-term impact of Stratus and its potential evolution.

Key Takeaways

• The new COVID-19 variant Stratus (XFG) is rapidly spreading, characterized by a high prevalence of hoarseness.
• While the overall public health risk remains low, its rapid spread necessitates continued monitoring.
• Stratus exhibits mutations that enhance its ability to evade immune defenses.
• Current COVID-19 vaccines are expected to remain effective against Stratus, but this will be continuously evaluated.
• The distinctive symptom of hoarseness, combined with other common COVID-19 symptoms, complicates clinical differentiation from other respiratory illnesses.