It’s that time of year when coughs and colds are rampant and everyone appears to be getting ill.

But health experts have warned that this winter could be one of the most worst yet - with the most severe flu outbreak in decades already wreaking havoc on the NHS.

The new H3N2 strain has been labelled as “unpleasant” by health bosses, who have warned the NHS could face a “tidal wave” of illness ahead of Christmas.

Hospital admissions for flu are already up 56 per cent when compared with the same week last year, with experts warning the peak of the season is yet to come. Health bosses have told Britons to wear a face mask outside if they feel unwell and encouraged those eligible to get their vaccination.

With cases on the rise, The Independent spoke to Dr Giuseppe Aragona, GP and medical adviser for Prescription Doctor, about how worried we should be over H3N2 and how to prevent it.

What is the H3N2 strain?

H3N2 is a strain of the influenza virus that is recognised as one of two widely circulating strains. Also known as subclade K, it is currently the most dominant strain in England, according to the UK Health Security Agency (UKHSA).

The H3N2 strain is currently the most dominant strain in England (Getty/iStock)

Dr Aragona explained that the letters and numbers refer to the virus’s surface proteins, haemagglutinin (H) and neuraminidase (N).

He said this particular combination can sometimes cause more severe illness, especially in older people or those with underlying health conditions.

“H3N2 changes regularly, so the version of the virus circulating this year may be different from previous years or from the one in the seasonal vaccine, which can make people more susceptible,” he added.

What are the symptoms?

Flu signs and symptoms develop very rapidly and extreme tiredness is common, which differs from the symptoms of colds which occur more gradually, according to the UKHSA.

The symptoms and severity of H3N2 illness have been similar to seasonal flu, including fever, cough, runny nose, and possibly other symptoms, such as body aches, vomiting, or diarrhoea.

People who are considered at high risk for developing flu-related complications include: children less than five years of age (especially children less than two years of age), adults 65 years of age and older, pregnant women, and people with certain chronic medical conditions like asthma, diabetes, heart disease, weakened immune systems, and neurological conditions.

If you develop flu symptoms after having direct or close contact with swine, contact your doctor and tell them your symptoms and about your contact with pigs.

How high are the flu rates at the moment?

Every day last week 1,717 patients were admitted to hospitals in England with the infection, up 56 per cent on the same week last year, according to NHS England.

The rates are seven times as high as in 2023, when there was an average of 243 flu patients a day.

It also follows the biggest flu season in Australia’s history, which is often seen as an accurate predictor of what the UK can expect.

Why is H3N2 so bad this winter?

Dr Aragona said there are a few different reasons why flu is expected to be particularly bad this winter.

Firstly, he explained that the flu season has started earlier than usual, which gives the virus more time to spread.

He added it has also “evolved” from the strain last year, meaning previous immunity or even the vaccine may offer less protection than usual.

“Fewer people have been exposed to flu in recent years, especially children, which leaves more people vulnerable,” he said. “On top of that, colder weather, indoor mixing, and social habits all contribute to faster transmission, creating the perfect storm for higher flu rates.”

Experts previously warned that the strain developed seven new mutations over the summer, meaning it is quite different from the previous strain included in this year’s vaccine.

The UK is braced for a spate of flu deaths this winter, with NHS leaders issuing a “flu jab SOS” urging people to get protected.

Last winter there were around 8,000 deaths associated with flu, according to the UKHSA. This figure is higher than the approximately 3,500 deaths recorded the year before, but lower than during the 2022 to 2023 season, when there were around 16,000 deaths.

How can you prevent yourself from getting the flu?

Dr Aragona said the “most effective” way to protect yourself from H3N2 is to get the flu vaccine - especially if you are in a “higher-risk group” such as over 65, pregnant, very young, or living with a long-term health condition.

“The vaccine may not prevent every infection, but it significantly reduces the risk of severe illness and hospitalisation,” he said.

Public health experts have urged all those eligible for the flu vaccine this winter to get the jab (PA)

Dr Aragona added that protection can be improved by maintaining good hand hygiene, covering your mouth and nose when coughing or sneezing, avoiding close contact with ill people, and keeping your home well-ventilated.

New data published by the UKHSA this week shows the 2025-2026 vaccine is currently 70 to 75 per cent effective at preventing hospital attendance in children aged two to 17 years, and 30 to 40 per cent effective in adults.

Dr Jamie Lopez Bernal, consultant epidemiologist for immunisation at UKHSA, said the results provide “reassuring evidence” that the season’s flu vaccines can offer important protection despite concerns about the new subclade.

He “strongly encouraged” everyone eligible to take up their flu vaccine “as soon as possible”, calling it the “best defence” against serious illness.

Dr Thomas Waite, deputy chief medical officer, said: “Flu can be an unpleasant infection for many and life-threatening for some; vaccination is the best form of defence.

“Early data from the UKHSA shows this year’s vaccine is continuing to provide good protection against flu variants circulating this year. The flu season has started early this year. Now is the time to get vaccinated if you are eligible.”

Last year’s flu vaccine had a significant impact on reducing severe illness, ranging from an almost 40% reduction in the number of those aged 65 and over being hospitalised, and a 75% reduction in those aged between 2 and 17 years.

How worried should we really be about H3N2?

Dr Aragona said while flu can be “unpleasant” for most healthy adults and children, he warned against panic as it is usually “manageable”.

“However, for older people, those with chronic illnesses, and other vulnerable groups, H3N2 can be serious, and this season may place extra pressure on the health service due to the early start and the strain’s characteristics,” he said.

“The important thing is to be vigilant: get vaccinated, take sensible precautions, and seek help early if symptoms become severe. With these steps, the risk can be managed effectively, even in a year when flu is circulating more widely.”