Britain experiences a notable rise in Covid infections linked to the emergence of the new Stratus and Nimbus strains, prompting renewed calls for precautions despite no increase in severity.
Britons have been advised to wear masks in crowded public spaces and to isolate if they test positive for Covid-19, amid a notable surge in cases driven by two new variants of the virus. These strains, named XFG (commonly called Stratus) and NB.1.8.1 (dubbed Nimbus), are behind a rapid increase in infections, with cases having doubled since August.
Professor Lawrence Young, a virologist at Warwick University, described the rise in cases and hospitalisations as “worrying so early in the Autumn period.” He attributed this to several factors, including the return of children to school, colder weather prompting more indoor gatherings in poorly ventilated spaces, and waning immunity in the population. The UK Health Security Agency (UKHSA) recently reported an increase in positivity rates from 7.6% to 8.4% in a week, alongside a rise in Covid admissions from 2.0 to 2.73 per 100,000 people.
While neither the Stratus nor Nimbus variants appear to cause more severe illness than previous Covid strains, genetic changes in the virus are enabling infections to become more contagious. Stratus, first detected in Southeast Asia in January and now dominant in the UK, is particularly associated with a persistent dry cough, tiredness, fever, and uniquely, a ‘razor blade’ sore throat. Nimbus, first identified in China and now spreading across Europe and the US, may trigger gastrointestinal symptoms such as nausea, vomiting, diarrhoea, and constipation.
Experts are urging people to take sensible precautions amid this surge. Although it is no longer legally required to isolate after testing positive, the UKHSA advises voluntary isolation to protect vulnerable groups. Professor Young emphasised personal responsibility, recommending testing and isolation until no longer infectious. Similarly, Professor Stephen Griffin of the University of Leeds highlighted the importance of reducing mixing in confined spaces and wearing masks, especially filtering types like FFP2 or FFP3, in crowded or poorly ventilated environments.
Professor Griffin, who himself has experienced long Covid, stressed that Covid remains a serious illness, capable of causing both acute symptoms and long-term effects, regardless of prior health or previous infection history. He criticised the current approach encouraging children with symptoms to attend school, advocating instead for isolation to prevent spread. He also called for improved indoor air quality as part of broader public health measures.
The government’s winter vaccination campaign has recently been launched, urging those eligible—such as over-75s, immunocompromised individuals, care home residents, pregnant women, and children—to receive their Covid booster alongside flu vaccines. While Covid tests are no longer free on the NHS, they remain accessible through pharmacies. Some private clinics also offer booster shots, albeit at significant cost.
The UKHSA estimates that Stratus accounts for about 63% of monitored cases in the UK, with Nimbus comprising roughly 25%. Despite their high transmissibility, current evidence does not indicate these variants cause more severe illness than earlier Omicron strains, according to the World Health Organization. Health officials continue to advise that people with respiratory infection symptoms, especially if unwell, should stay home and minimize contact with vulnerable individuals, using masks if going out is unavoidable.
UK ministers have reiterated they are unlikely to impose new lockdowns unless a significantly more dangerous variant emerges. Instead, they rely on public responsibility and vaccination to manage the evolving Covid landscape, which remains dynamic as new variants like Stratus and Nimbus take hold.
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Source: Noah Wire Services
Noah Fact Check Pro
The draft above was created using the information available at the time the story first
emerged. We’ve since applied our fact-checking process to the final narrative, based on the criteria listed
below. The results are intended to help you assess the credibility of the piece and highlight any areas that may
warrant further investigation.
Freshness check
Score:
7
Notes:
The narrative mentions a surge in cases due to two new variants, Stratus (XFG) and Nimbus (NB.1.8.1), with cases doubling since August. The earliest known publication date for similar content is 1 October 2025, with reports from The Week and The Independent. The Daily Mail article appears to be a recent publication, but the information is not entirely new. The presence of a press release suggests a high freshness score, but the recycled nature of the content warrants a slight reduction.
Quotes check
Score:
6
Notes:
The narrative includes quotes from Professor Lawrence Young and Professor Stephen Griffin. Similar quotes have appeared in earlier material, indicating potential reuse. The wording varies slightly, but the core message remains consistent. The lack of online matches for some quotes suggests potential originality, but the similarities to earlier reports raise concerns about exclusivity.
Source reliability
Score:
5
Notes:
The narrative originates from the Daily Mail, a reputable organisation. However, the presence of a press release and the recycled nature of the content from other outlets like The Week and The Independent introduce some uncertainty. The reliance on a single source for the majority of the information raises questions about the comprehensiveness and verification of the content.
Plausability check
Score:
8
Notes:
The narrative presents plausible claims about the rise of new Covid variants, Stratus and Nimbus, and their associated symptoms. These claims are supported by reports from reputable outlets like The Week and The Independent. The information aligns with known patterns of variant emergence and public health responses. However, the reliance on a single source and the recycled nature of the content slightly diminish the overall credibility.
Overall assessment
Verdict (FAIL, OPEN, PASS): OPEN
Confidence (LOW, MEDIUM, HIGH): MEDIUM
Summary:
The narrative presents information about the surge of new Covid variants, Stratus and Nimbus, with some details corroborated by reputable sources. However, the recycled nature of the content, reliance on a single source, and the presence of a press release introduce uncertainties regarding freshness and originality. The lack of exclusive content and potential reuse of quotes further complicate the assessment.
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