- “Stratus” = XFG lineage. WHO classifies XFG as a Variant Under Monitoring (VUM) and currently judges its added public‑health risk as low. Vaccines are still expected to work against symptomatic and severe disease. [1]
- Now the most common lineage worldwide. WHO’s dashboard shows XFG made up ~67% of sequences by late August 2025, up from 58% earlier in the month. [2]
- Symptoms to watch: a hoarse/raspy voice is frequently reported early, alongside the usual COVID signs (dry cough, fatigue, fever, sore throat). Brain fog and persistent cough are also noted. Most cases remain mild in vaccinated people. [3]
- US picture, late September: CDC says overall respiratory illness activity is very low, with COVID activity having peaked and declining in many areas. Wastewater “variant” data now broadly tracks XFG as dominant. [4]
- Recent spike headlines: Earlier this week Fox News, citing CDC indicators, highlighted nine states with rising COVID markers (NY, NJ, DE, VT, MI, WI, MN, ND, SD). Trends can change quickly and differ by metric. [5]
- UK snapshot: UKHSA’s latest explainer lists XFG/XFG.3 (“Stratus”) and NB.1.8.1 (“Nimbus”) as the most common current lineages in England; no signal of greater severity. [6]
- How it compares: WHO says XFG shows only “marginal” extra immune evasion versus other JN.1‑family strains (e.g., LP.8.1); Nimbus is also assessed low risk. [7]
- Vaccines & timing: FDA advised 2025–26 vaccines be monovalent JN.1‑lineage (preferably LP.8.1). Experts emphasize timing doses around periods of higher risk and personal circumstances. [8]
- Tests & masks still matter: FDA/CDC continue to recommend repeat home antigen testing after a negative, and confirmatory PCR when needed. NIOSH‑approved N95s offer the highest wearer protection among consumer options. [9]
What is the “Stratus” COVID variant?
“Stratus” is the colloquial name for XFG, a recombinant Omicron descendant (from LF.7 and LP.8.1.2). WHO added XFG to its monitoring list in late June and, based on available evidence, concluded the “additional public‑health risk … is low.” WHO’s lab summary notes spike‑protein changes (e.g., at positions 478 and 487) that can modestly increase immune escape compared with earlier JN.1‑family strains. [10]
Globally, XFG gained speed over the summer. WHO’s dashboard reports XFG was ~67% of submitted sequences in the week ending 31 Aug 2025; the runner‑up, NB.1.8.1 (“Nimbus”), accounted for ~21%. [11]
WHO: XFG “exhibits only marginal additional immune evasion” versus LP.8.1, with no evidence of higher severity so far. [12]
Where is it rising right now?
- United States. CDC’s Respiratory Illnesses Data Channel says overall ARI (acute respiratory illness) levels are very low nationally as of Sept 26, and COVID activity has peaked and is declining in many regions—though ED visits and hospitalizations remain elevated relative to baseline. Wastewater trend pages show XFG dominating variant signals. [13]
- Recent “9 states” headline. A Fox News roundup (Sept 25) pointed to CDC indicators showing rising COVID activity earlier this month in NY, NJ, DE, VT, MI, WI, MN, ND, SD. That snapshot reflects specific weeks/metrics; CDC’s Rt page now shows most states stable or declining as of Sept 23. In short: local curves can move quickly. [14]
- United Kingdom. UKHSA’s 25 Sept explainer: the most common current variants are XFG/XFG.3 and NB.1.8.1; no evidence they cause more severe disease than predecessors. Recent surveillance tallied 35% XFG.3, 28% XFG, 11% NB.1.8.1 in the sampled period. [15]
The UK’s official vaccine “Green Book” also notes XFG (“Stratus”) became the most prevalent lineage in July 2025 in England. [16]
The symptom profile: why a hoarse voice is getting attention
Clinicians in multiple reports have flagged hoarseness/raspy voice as a frequent early sign of Stratus, often preceding the classic fever/cough/fatigue. Wired called hoarseness a standout symptom, while Stony Brook Medicine lists a broader set: dry persistent cough, tiredness, fever, plus sore throat, chest tightness, shortness of breath, headaches/body aches, upset stomach/nausea/loss of appetite, brain fog, and loss of taste/smell (less common now). [17]
Stony Brook: “Most cases of COVID‑19 variant Stratus are mild, particularly if you’re vaccinated.” [18]
The Independent’s recent brief likewise highlights hoarseness and stresses there’s no signal of increased severity; UKHSA’s Dr Alex Allen reminds the public that “It is normal for viruses to mutate and change over time.” [19]
Vaccines: what we know about protection in the Stratus wave
WHO’s risk evaluation indicates current COVID vaccines “are expected to remain effective” against XFG for symptomatic and severe disease. That aligns with the FDA’s call for 2025–26 US vaccines to be monovalent JN.1‑lineage, preferably LP.8.1, to match currently circulating viruses. [20]
CDC’s fall updates emphasize staying up to date and tailoring timing to personal risk and exposure windows. As UVA’s Dr. Costi Sifri put it in an AP explainer, “You want to be fully protected at the time that it’s most important for you.” [21]
Testing and masks: what actually helps now
Testing. Rapid antigen tests still detect infectious cases but can miss early infections. FDA/CDC advise retesting 48 hours after a negative if you have symptoms or an exposure; seek PCR if results remain unclear or clinical stakes are high. [22]
Masks & respirators. CDC notes cloth masks provide the least wearer protection, surgical/disposable more, KN95‑type even more, and NIOSH‑approved N95s the most among consumer options when fit is good. For the best filtration and fit, look for NIOSH‑approved markings. [23]
Treatments and who’s at highest risk
Antivirals such as nirmatrelvir/ritonavir (Paxlovid) remain recommended for those at higher risk of severe COVID‑19; talk to your clinician promptly if you test positive and qualify. (WHO’s Nimbus review also found no evidence of increased antiviral resistance in that lineage; XFG assessments focus on immune‑evasion rather than drug resistance.) People ≥65, residents of long‑term care, and those with certain underlying conditions remain at higher risk and should prioritize vaccination and early treatment pathways. [24]
How “Stratus” compares with “Nimbus” and earlier waves
- Transmissibility & growth. Both XFG (“Stratus”) and NB.1.8.1 (“Nimbus”) grew rapidly in different regions this year. WHO’s side‑by‑side risk briefs rate both as low risk overall, with marginal additional immune escape versus LP.8.1. [25]
- Mutations. XFG carries spike changes including F456L, T478K, and N487D; Nimbus features F456L and T478I, among others—differences that likely explain minor shifts in neutralization without clear severity signals so far. [26]
- Symptoms. The “razor‑blade sore throat” chatter circulated during the Nimbus month, while hoarseness has been a frequent anecdotal early sign with Stratus. Both still present like Omicron‑family COVID overall. [27]
The UK and US public‑health stance right now
- UKHSA: Most common strains are XFG/XFG.3 and NB.1.8.1, with no severity signal; keep up with seasonal vaccination if eligible and follow “stay home if unwell” advice to protect vulnerable people. [28]
- CDC: As of Sept 26, respiratory illness is very low nationally; COVID activity is easing in many areas, though hospital metrics are still elevated relative to the summer floor. Wastewater dashboards remain useful early indicators, and the variant panel shows XFG dominance. [29]
Practical checklist (compare your options)
- If you feel a sudden hoarse/raspy voice, especially with cough/fever/fatigue, test at home and retest after 48 hours if negative. PCR can confirm if stakes are high (travel, visiting high‑risk relatives). [30]
- Mask smarter when risk is up: Prefer NIOSH‑approved N95 for the best wearer protection; surgical/disposable masks help; cloth alone protects least. Fit matters. [31]
- Ventilate and filter (open windows, use HEPA room filters) in gatherings—still some of the highest‑ROI steps. (CDC bundles this advice in its respiratory‑virus prevention pages.) [32]
- Time your vaccine. FDA has set 2025–26 shots to JN.1‑lineage; plan dosing to precede higher‑risk periods or surges. Seek early antivirals if you’re eligible and test positive. [33]
What experts are saying
- WHO: The “additional public health risk posed by XFG is evaluated as low,” and vaccines are still expected to protect against symptomatic and severe disease. [34]
- UKHSA’s Dr Alex Allen: “It is normal for viruses to mutate and change over time,” with no current sign that XFG/XFG.3 causes more severe disease or undermines vaccines. [35]
- AP interview—Dr. Costi Sifri (UVA Health): “You want to be fully protected at the time that it’s most important for you,” underlining personal timing for boosters. [36]
- Stony Brook Medicine: “Most cases … are mild, particularly if you’re vaccinated,” but seek care if symptoms worsen or you’re high‑risk. [37]
The bottom line
- Stratus (XFG) has overtaken other lineages and is dominant in sequencing globally; its symptom profile often starts with hoarseness but otherwise mirrors Omicron‑era COVID. Vaccines still work, and N95‑level masking and repeat antigen testing remain effective tools. For most healthy, up‑to‑date adults, the individual risk remains similar to recent COVID waves. [38]
Sources used in this report (selected)
- World Health Organization: XFG risk evaluation (25 Jun 2025) and global dashboard update (Aug–Sept 2025). [39]
- UK Health Security Agency: Current variants explainer (25 Sept 2025). [40]
- FDA: 2025–26 vaccine composition guidance (JN.1‑lineage). [41]
- CDC: Respiratory Illnesses Data Channel (Sept 26), NWSS variant/wastewater pages. [42]
- Clinical & media: Stony Brook Medicine explainer (symptoms, severity), Wired (hoarseness), The Independent (bulletin & Q&A), Fox News (state spikes citing CDC). [43]
Transparency note: You also shared a Daily Record link. That site blocks our access for citation, so we validated its key claims (symptoms, prevalence, risk) via UKHSA, WHO and The Independent instead. [44]
If you’d like, I can tailor a short “travel‑ready” checklist (vaccination timing, testing protocol, what to pack) for your location and risk profile using these findings.
References
1. www.who.int, 2. data.who.int, 3. www.wired.com, 4. www.cdc.gov, 5. www.foxnews.com, 6. ukhsa.blog.gov.uk, 7. www.who.int, 8. www.fda.gov, 9. www.fda.gov, 10. www.who.int, 11. data.who.int, 12. www.who.int, 13. www.cdc.gov, 14. www.foxnews.com, 15. ukhsa.blog.gov.uk, 16. assets.publishing.service.gov.uk, 17. www.wired.com, 18. health.stonybrookmedicine.edu, 19. www.the-independent.com, 20. www.who.int, 21. apnews.com, 22. www.fda.gov, 23. www.cdc.gov, 24. cdn.who.int, 25. www.who.int, 26. www.who.int, 27. www.the-independent.com, 28. ukhsa.blog.gov.uk, 29. www.cdc.gov, 30. www.fda.gov, 31. www.cdc.gov, 32. www.cdc.gov, 33. www.fda.gov, 34. www.who.int, 35. www.the-independent.com, 36. apnews.com, 37. health.stonybrookmedicine.edu, 38. data.who.int, 39. www.who.int, 40. ukhsa.blog.gov.uk, 41. www.fda.gov, 42. www.cdc.gov, 43. health.stonybrookmedicine.edu, 44. ukhsa.blog.gov.uk
