Just when it felt like the COVID variant conversation had quieted down, a new name is making the rounds: XFG, informally referred to as Stratus.

You might remember that we had previously covered NB.1.8.1, the dominant variant in Australia. And did you know it was nicknamed Nimbus? Now, before you assume the World Health Organization is pulling inspiration from Harry Potter, it’s worth noting that nimbus and stratus are actually types of clouds, not broomsticks. Still, it does make tracking new strains feel oddly atmospheric.

So, what’s the story with Stratus? According to the WHO, XFG was designated a Variant Under Monitoring (VUM) in late June 2025, after being detected in samples as far back as January. It’s now on the rise globally and has started to show up in Australia.

But here’s the reassuring part: the global public health risk posed by XFG is currently considered low. And more importantly, existing COVID-19 vaccines are expected to remain effective against both symptomatic and severe disease caused by this variant.

In this article, we’ll break down what XFG is, where it’s been found, what symptoms to watch for, and why it’s worth knowing about.

What is the XFG (Stratus) variant?

The XFG variant — now informally known as Stratus — is one of the newer SARS-CoV-2 strains being tracked by the World Health Organization (WHO). It was officially designated a Variant Under Monitoring (VUM) on 25 June 2025, after scientists began observing a gradual increase in its global presence.

What makes XFG different from some earlier variants is that it’s a recombinant — meaning it’s a blend of two existing SARS-CoV-2 lineages. In this case, it’s a genetic mix of LF.7 and LP.8.1.2, with the earliest known sample collected in late January 2025.

Image via @TRyanGregory
(Source: https://x.com/username/status/1234567890)

Recombinant variants like this occur when two distinct viral strains infect the same individual and exchange genetic material, creating a new version with features from both. This process isn’t unusual and doesn’t necessarily mean the new variant is more dangerous — but it does warrant closer monitoring.

So far, XFG doesn’t appear to cause more severe illness than previous variants. The WHO currently assesses the global public health risk as low, based on the data available. However, what has prompted increased attention is its rising proportion in global sequence data — indicating that it may be more transmissible than other circulating strains in certain regions.

We’ll take a closer look at where it’s spreading — including what the latest data shows for Australia.

Where has XFG been detected so far?

Since it was first identified in late January 2025, the XFG variant (Stratus) has steadily appeared in more parts of the world — enough that the World Health Organization has now included it on its Variant Under Monitoring list.

As of late June, XFG has been detected in 38 countries, and its presence is gradually increasing. According to the WHO, it currently accounts for approximately 22.7% of all globally reported SARS-CoV-2 sequences, showing signs that it may be outcompeting other strains in some regions.

One country seeing a significant rise in cases is India, where XFG appears to be the dominant strain. Some of the first reports of symptoms specific to this variant — such as hoarseness — have come from doctors observing patients there.

In Australia, XFG is still emerging but remains at low levels for now. As of June 29, Australia’s national genomic surveillance platform reported:

• NB.1.8.1 is still the dominant variant, making up 48.6% of sequenced cases
  

• XFG represents approximately 5% of cases, with 24 total sequences

This increase — though still small — suggests that XFG is on the rise, and health authorities are keeping a close eye on its growth.

Symptoms — Is XFG different from other variants?

So far, the XFG (Stratus) variant appears to cause symptoms that are mostly consistent with other recent COVID-19 strains, particularly those in the Omicron family. For most people, this includes a mix of respiratory and cold-like symptoms such as:

• Sore throat
  
  
• Fatigue
  
  
• Headache
  
  
• Nasal congestion or runny nose
  
  
• Cough
  
  
• Fever (in some cases)

However, early observations from doctors in India, where XFG is currently the dominant strain, have noted one symptom standing out a little more than usual: hoarseness or a raspy voice.

While hoarseness has been reported in previous COVID waves, it seems to be appearing more frequently with XFG. This could be due to the variant’s effect on the upper airways, though more data is needed to confirm whether it’s a true hallmark of this strain or simply a regional trend.

Importantly, there is no current evidence that XFG causes more severe illness than other circulating variants. Like many Omicron-related strains, it appears to result in mild to moderate symptoms for most people, particularly those who are vaccinated or have some level of prior immunity.

If you’re experiencing any COVID-like symptoms — especially during flu season — it’s still a good idea to test, rest, and follow local health advice to prevent further spread.

Are current vaccines still effective?

One of the first questions people often ask when a new COVID-19 variant emerges is: Do the current vaccines still work?

When it comes to XFG (Stratus), the short answer is: yes — though more research is still underway. At this stage, the World Health Organization expects existing COVID-19 vaccines to remain effective, particularly in protecting against severe illness and symptomatic infection.

That said, researchers are still evaluating exactly how well the newest vaccines perform against this specific strain.

Here’s what we know so far:

• The latest COVID-19 vaccines were designed to target the JN.1 Omicron subvariant, which is closely related to XFG.
  

• In lab-based studies, scientists tested whether antibodies produced by the current vaccine could block a "pseudovirus" similar to XFG from entering human cells.
  

• Results showed that XFG-like pseudoviruses were able to partially evade antibodies — slightly more than JN.1 — but not completely.
  

• This suggests that while XFG may have some immune escape properties, the current vaccines should still offer a reasonable level of protection.

In short: while the effectiveness may be slightly reduced, especially against mild infections, vaccines continue to play a key role in reducing the risk of severe disease, hospitalisation, and complications — which is what matters most.

Health authorities have not recommended any changes to vaccine guidance based on XFG so far, and booster doses are still encouraged, especially for high-risk individuals.

What is a Variant Under Monitoring (VUM)?

You may have seen the term “Variant Under Monitoring” (VUM) linked to XFG in recent reports — but what exactly does that mean?

A VUM is a designation used by the World Health Organization (WHO) to flag a SARS-CoV-2 variant that has certain genetic changes which may affect how it spreads, how it interacts with our immune system, or how severe it could become. At the time it's classified as a VUM, there's not yet enough evidence to confirm whether the variant poses a real risk.

Essentially, it tells public health authorities, “This variant could matter — let’s keep an eye on it.”

According to the WHO, the main purpose of this classification is to determine whether a variant (or any related strains) might present an added threat to global public health compared to other circulating strains.

As of now, XFG is one of seven VUMs being monitored globally. It’s not a Variant of Interest or Variant of Concern — those labels are reserved for variants that show clearer signs of increased risk in terms of spread, severity, or immune evasion.

If you’re curious about what other variants are on the list, the WHO regularly updates their tracker here: WHO COVID-19 Variant Tracking Dashboard

Recently tracked COVID-19 variants

The World Health Organization (WHO) regularly monitors the evolution of SARS-CoV-2 variants around the world. As the virus continues to mutate, some new strains are designated for close observation — especially if they show signs of spreading faster, dodging immunity, or behaving differently from known variants.

These variants are grouped into three main categories:

• Variants Under Monitoring (VUM)
  

• Variants of Interest (VOI)
  

• Variants of Concern (VOC)

At the time of writing (July 2025), there are seven active Variants Under Monitoring. Here’s a look at those currently on the WHO’s radar:

Variants Under Monitoring (VUMs)

These are variants that show genetic changes potentially linked to altered behaviour but haven’t yet shown strong evidence of increased risk.

 

Note: The classification of variants is subject to change as new data emerge. The WHO and other health authorities continue to assess these variants for potential impacts on transmissibility, disease severity, and vaccine effectiveness.

Conclusion

As new COVID-19 variants like XFG (Stratus) emerge, it’s natural to feel curious — and maybe a little uneasy. But right now, the message from global health authorities is clear: this variant is being watched, not feared.

XFG is spreading in parts of the world and showing up more frequently in sequencing reports — but current vaccines are still expected to offer protection, and the overall risk to public health remains low. Its classification as a Variant Under Monitoring simply means scientists are keeping a close eye on how it behaves.

If you’re already staying up to date with your boosters, practicing good hygiene, and paying attention to public health advice, you’re doing everything right. As always, staying informed is one of the best tools we have.

And if your voice sounds a little hoarse this week? It’s probably just a cold or seasonal bug… but a rapid test never hurts — especially with new variants like XFG circulating. The Sonictec 5-in-1 Combo Rapid Antigen Test is a convenient option that can check for COVID-19, influenza A & B, RSV, and adenovirus — all in one simple test. It’s a great way to get clarity on your symptoms quickly, whether you're at home or at work.

Test, Protect, Clean: All Your Essentials in One Place

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