The World Health Organization has designated a new COVID-19 subvariant, known as XFG or “Stratus,” as a “variant under monitoring” due to its rapid spread and potential implications for public health. As of late June, XFG has been identified in 38 countries, including significant detection rates in India, Spain, the UK, and the US.
Understanding the Impact of XFG
XFG is a recombinant subvariant of the Omicron lineage, specifically formed from the merger of LF.7 and LP.8.1.2 subvariants. Recombinant variants, indicated by an “X” in their name, are created when two different subvariants exchange genetic material. This process can sometimes lead to increased immune evasion, as seen with XFG, which has been shown in early studies to reduce antibody effectiveness nearly two-fold compared to previous strains.
Despite these findings, current evidence does not suggest that XFG causes more severe illness than other variants. However, the subvariant’s ability to spread rapidly is a concern, with XFG comprising 22.7% of global sequences by late June, a significant rise from the previous month.
Global Spread and Monitoring
The first sample of XFG was collected on January 27. The global database, GISAID, has reported 1,648 XFG sequences, indicating a swift increase in its prevalence. According to Mike Honey, an Australian data expert, XFG detection rates are notably high in India (over 50%), Spain (42%), and exceed 30% in both the United Kingdom and United States.
In Australia, the subvariant NB.1.8.1 remains dominant, but XFG has begun to establish a presence, accounting for about 5% of sequences in recent reports. This trend suggests that XFG may soon become more prevalent globally.
While the WHO currently assesses the global risk posed by XFG as low, vigilance remains crucial. The organization continues to recommend vaccination and early use of antivirals for those eligible. Preventative measures, such as wearing masks in crowded settings and improving air quality, are also advised to minimize transmission risks.
Vaccine Efficacy and Public Health Guidance
Current COVID-19 vaccines are expected to remain effective against XFG, particularly in preventing severe disease. However, the virus’s ongoing evolution necessitates regular vaccine updates. The most recent update targets the JN.1 subvariant, with which XFG shares lineage.
In Australia, vaccine uptake remains a challenge, with only 32.3% of individuals aged 75 and over receiving a vaccine in the past six months. Efforts to improve vaccination rates across all age groups are critical in maintaining public health resilience against emerging variants like XFG.
As researchers continue to study XFG, public health officials emphasize the importance of staying informed and adhering to recommended health practices to mitigate the impact of new subvariants on global health systems.
