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XFG ‘Stratus’: The Rising COVID Variant Being Closely Watched by WHO

A newly identified COVID-19 subvariant XFG, nicknamed “Stratus,” is drawing international attention as it climbs the ranks of global prevalence. On June 27, the World Health Organization (WHO) officially added XFG to its “variants under monitoring” list, flagging it for further scrutiny due to its potential to spread rapidly and evade immune defenses.

COVID-19 subvariant XFG is a recombinant variant, meaning it formed through the combination of two existing lineages, LF.7 and LP.8.1.2. The “X” prefix signifies this genetic fusion. Scientists have identified four mutations in the spike protein, particularly at positions 478 and 487, which are linked to increased immune evasion. Though similar to the previously tracked NB.1.8.1 variant (nicknamed “Nimbus”), Stratus is now emerging as a contender for global dominance.

Global Spread and Rising Prevalence

Since its earliest detection on January 27, 2025, in Denmark, COVID-19 subvariant XFG has expanded rapidly. As of June 22, over 1,600 sequences of the variant have been uploaded to the global database GISAID from 38 countries. XFG now accounts for nearly 23% of all weekly global sample,s up from just 7.4% a month earlier.

The variant has gained significant ground in India, where it represents more than 50% of sequenced cases. Similarly, it makes up around 42% in Spain, over 30% in the UK and the US, and is slowly growing in regions like Australia, where it comprises 5% of current cases. Experts note this growth mirrors the rise of previous dominant variants, signaling that XFG could soon take the lead globally.

COVID-19 subvariant XFG Symptoms, Severity, and Vaccine Protection

Clinically, XFG does not appear more severe than previous variants. The most notable symptom linked to it is hoarseness or a scratchy throat, alongside typical signs like dry cough, mild fever, and fatigue. These presentations remain largely mild to moderate in vaccinated individuals.

What distinguishes XFG, however, is its ability to partially escape neutralizing antibodies, potentially at double the rate of earlier Omicron subvariants. Despite this, experts stress that current vaccines continue to offer strong protection against severe disease and hospitalization. WHO has emphasized that while XFG poses a low global risk at this stage, ongoing booster campaigns and public health measures like masking in enclosed spaces remain essential as the virus continues to evolve.

As COVID-19 subvariant XFG “Stratus” spreads across continents, scientists and health agencies are intensifying their efforts to monitor and study its trajectory. While its high transmission and immune evasion capacity are noteworthy, there is no evidence yet of increased disease severity. With strong vaccination coverage and public vigilance, global health authorities remain cautiously optimistic, but alert.