Two new Covid-19 variants, known as XFG or Stratus, and NB.1.8.1 or Nimbus, are currently circulating in the UK. According to the UK Health Security Agency (UKHSA), these variants do not seem to cause more severe illness than previous strains, although recent genetic changes may have increased their transmissibility. Stratus has become the dominant strain in England, accounting for about 30% of cases, while Nimbus represents roughly a quarter of monitored infections. The UKHSA has categorised Stratus as a "variant under monitoring" due to its rising prevalence.

Experts note that typical Covid symptoms caused by these variants remain consistent with earlier strains. Common signs include cough, fever, fatigue, headache, muscle aches, and loss of taste or smell. Unique to Stratus, a hoarse voice has been highlighted as a distinctive symptom, whereas Nimbus has been linked to a particularly painful sore throat, often described as a "razor-blade" sensation. Additional symptoms for Nimbus may include sneezing, runny nose, congestion, and gastrointestinal issues such as nausea, vomiting, or diarrhoea.

Despite the mild nature of most infections, the risk of serious illness remains concentrated among older adults—particularly those aged 75 and over—and individuals with underlying health conditions such as chronic kidney disease, diabetes, or compromised immune systems. Warning signs that should prompt urgent medical advice include confusion, persistent high fever, breathlessness, and markedly reduced oxygen levels. For older patients, symptoms that persist or worsen over several days, including severe fatigue or loss of appetite, also require vigilance.

The decline in vaccine uptake among older populations is a significant concern for public health experts. Uptake of Covid vaccines has been falling year by year, with recent figures showing about 60% coverage among those over 75, which falls short of recommended levels. There is a persistent misconception that current vaccines are ineffective against emerging variants; however, scientific evidence firmly supports that vaccines continue to provide protection against severe disease caused by the existing strains, including Stratus and Nimbus. Public health professionals strongly recommend that older adults receive Covid vaccinations twice annually, typically in spring and autumn, which are provided free on the NHS.

Laboratory research sheds light on the differences between these variants. Nimbus exhibits a strong affinity for the ACE2 receptor in human cells, which facilitates its infectivity. Meanwhile, Stratus possesses mutations that enhance its ability to evade antibodies, potentially making it more contagious. Nonetheless, neither variant has led to a significant surge in hospitalisations or more severe clinical outcomes, according to current surveillance data. Amid these developments, health authorities continue to urge caution—encouraging individuals to avoid contact with vulnerable people when possible and to self-isolate if symptomatic.

In summary, while the Stratus and Nimbus Covid variants have increased transmissibility and distinctive symptomatic profiles, they do not currently pose a greater threat of severe illness compared to previous variants. Continued vaccination efforts, especially targeting older and vulnerable groups, remain pivotal in mitigating the impact of these evolving strains and enabling society to live as normally as possible.

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Source: Noah Wire Services