Britain is currently experiencing an unprecedented surge in flu cases, with health experts warning that "there is no peak in sight." New figures reveal a dire situation for the NHS this December, as flu hospitalisations have risen by over 55 percent in just one week. An average of 2,660 patients per day were hospitalized with flu last week, marking the highest number ever recorded for this time of year and equivalent to filling more than three entire hospital trusts daily. Surveillance programs indicate that flu hospital admissions in England are more than double last year's figures for the same period and ten times higher than in 2023, prompting health leaders to suggest this could be the worst flu season in decades. Professor Paul Hunter, a virologist at the University of East Anglia, notes that "given the early upswing in infections, the new variant and what we know from elsewhere in the world, like Australia... it does look as if this year will be as bad as we have seen at least in the last decade."

The current outbreak is largely driven by a mutated strain of the H3N2 influenza virus, dubbed subclade K or the 'super flu'. This strain has undergone seven mutations over the summer, enabling it to evade previous immunity and making it "hotter" and "nastier" as well as more infectious, according to virologists. Professor Punam Mangtani, an epidemiologist at the London School of Hygiene & Tropical Medicine, explains that H3N2 is less similar to strains seen in recent years, leading to less existing immunity in the population, which facilitates easier transmission and earlier rises in cases, particularly among teenagers, young adults, and then younger children.

Health officials strongly advocate for the flu jab as the "best defence" against the virus. The annual vaccination programme commenced on October 1st, targeting individuals aged 65 and over, those under 65 in clinical risk groups, care home residents, carers, pregnant women, close contacts of immunosuppressed individuals, and front-line health and social care workers, as well as children. Private vaccinations are also available for around £20. While the jab may not prevent infection, it significantly reduces the risk of severe disease. Data from the US CDC for the 2023-2024 Covid vaccines showed a roughly 50 percent reduction in hospitalisation among older adults in the first two months post-vaccination, though protection wanes after about four months. Professor Hunter highlights that Australian data revealed approximately 80 percent of hospitalised flu patients were unvaccinated, underscoring the importance of vaccination for eligible individuals. Despite these benefits, last year's vaccine uptake was only 60 percent, falling short of the 75 percent target, leading to the establishment of pop-up vaccination centres in various community locations.

Typical symptoms of the H3N2 'super flu' mirror those of seasonal flu, including fever, cough, runny nose, body aches, and sometimes vomiting or diarrhoea. Symptoms usually manifest one to three days after infection, and while most cases resolve within a week, exhaustion and a lingering cough can persist for weeks. Professor Hunter currently sees "no indication... that this year's flu is any more severe than previous strains" for adults, but cautions that Australia's recent flu season saw a number of children hospitalised, stressing the need to monitor children's symptoms and ensure their vaccination.

Experts suggest this will be the worst flu season in years, though the peak is yet to be reached. Current cases and hospitalisations are worse than the same period last year, which peaked in January. Professor Julian Redhead, NHS England's national medical director for urgent and emergency care, confirmed, "Today's numbers confirm our deepest concerns: the health service is bracing for an unprecedented flu wave this winter."

The surge has severely impacted hospitals nationwide, with some declaring critical incidents, restricting visiting, and imposing mask orders. Critical incidents have been reported in at least six hospitals in the West Midlands, including those under University Hospitals Birmingham NHS Foundation Trust and University Hospitals of North Midlands trust. NHS Ayrshire and Arran in Scotland has cancelled routine visiting due to "significant pressure." Mandatory mask rules have been implemented in parts of hospitals across London, Berkshire, Surrey, Lincolnshire, Shropshire, and Oxfordshire.

Beyond vaccination, experts recommend several protective measures, many familiar from the pandemic: diligent hand washing, ensuring good ventilation, and considering mask-wearing. Professor Hunter notes that masks do help protect individuals and others from the virus, suggesting their use in crowded spaces or when interacting with vulnerable people, though he doesn't believe they should be mandatory. The virus spreads primarily through person-to-person contact via droplets from coughs, sneezes, or speech, which can travel up to six feet. Germs can also live on hands for up to 24 hours, making hand washing crucial. The UKHSA advises opening windows to bring in fresh air and remove virus particles.

The efficacy and necessity of public mask mandates remain a point of contention. Some experts, like Professor Stephen Griffin, a virologist at the University of Leeds, urge greater public mask usage, particularly for those who wish to avoid influenza or come into contact with vulnerable individuals. Dr Suzanna McDonald of the UK Health Security Agency advises symptomatic individuals to "consider wearing a face mask" and to stay home to limit spread. Professor Laurance Young of Warwick University recommends masking even with mild symptoms or when in crowded areas or near the elderly and immunocompromised. Many NHS Trusts have already mandated masks for patients and staff in healthcare settings. However, Emeritus Professor Robert Dingwall, a sociology expert in infectious diseases, disputes the effectiveness of masks, citing Cochrane Collaboration reviews that found "little or no benefit in interrupting transmission" for influenza-like illnesses. Despite expert recommendations, government figures, including Keir Starmer and the Prime Minister, currently have no plans to strengthen public guidance on mask-wearing, instead emphasizing "common sense" measures such as hand washing and ventilation. A YouGov poll indicated that 61 percent of people would be willing to wear a mask to prevent flu spread, while 33 percent would not.

A leading GP, Dr Donald Grant, warns that the scale of the flu outbreak could lead people to misinterpret the severity of their symptoms, potentially masking more serious, life-threatening conditions. He urges careful monitoring of symptoms and prompt medical attention when necessary. Key warning signs that should never be ignored include:

• Shortness of breath or chest pain: While common with flu, these could signal pneumonia, worsening underlying conditions like asthma or COPD, or even heart failure. Flu places stress on the body, increasing the risk of heart attacks, especially in older individuals.
• Fever lasting longer than five days: A typical flu fever peaks around three days. A persistent or worsening high temperature beyond four to five days could indicate pneumonia or a secondary bacterial infection, such as sepsis, a life-threatening overreaction of the body's immune system.
• Dehydration and inability to keep fluids down: Persistent vomiting or diarrhoea leading to inability to stay hydrated is atypical for flu and could signify a serious gastrointestinal illness or electrolyte imbalances, which can cause organ damage and be fatal.
• Confusion or other cognitive difficulties: Flu can cause fatigue, but confusion, difficulty concentrating, or extreme drowsiness are not typical. These symptoms often indicate low oxygen levels, severe dehydration, or sepsis, and require urgent medical attention. Low oxygen levels can trigger heart attacks, particularly in those with undiagnosed atherosclerosis.
• Symptoms improving, then suddenly getting worse: A "rebound effect" where symptoms initially improve then intensify could signal a secondary bacterial infection like bronchitis, an inflammation of the airways.
• Severe or unusual muscle pain: While body aches are common, intense muscle pain making movement difficult could indicate a more serious infection. In rare cases, it could be rhabdomyolysis, a condition where muscle tissue breaks down, leading to kidney and heart damage.

Professor Griffin concludes that "no single measure is going to be enough but by layering interventions you can minimise the risk, for yourself and others," advocating for a combination of vaccination, hand washing, ventilation, mask-wearing in specific situations, and self-isolation when symptomatic to collectively mitigate the risks of this severe flu season.