The UK is witnessing an earlier flu season than normal, following reports that parts of the United States is also seeing an early start to the season.
The NHS said it just witnessed its “busiest September ever” for patients attending A&E (2.44 million visits).
Professor Frankie Swords, NHS England’s national medical director, has warned that staff are seeing “ominous” signs of winter pressure already building and said more patients are heading to A&E with flu and other respiratory viruses than usual for this time of year.
Flu typically circulates later in the year, peaking in December, but data shows it’s been doing the rounds in the UK since mid-August.
According to the UK Health Security Agency (UKHSA), flu activity throughout September was higher than in the same period across the past four years.
Levels currently remain “low”, but experts are warning people who are eligible for the free flu vaccine to take up the offer sooner rather than later.
Antonia Ho, a professor of infectious diseases at the University of Glasgow’s Centre for Virus Research, told The Guardian that an early rise in flu cases “may indicate a more intense influenza season overall”.
This is because “earlier onset is associated with a longer period of community transmission and higher cumulative case numbers”, she said.
A spokesperson for UKHSA said the increases in flu are largely being driven by young adults (for example, when students began mixing at university), as well as children being back at school.
As expected for this time of year, Covid-19 activity has also been increasing for the past two months, although it is still deemed at low levels compared to previous years.
UKHSA’s spokesperson said “it’s not clear” why the flu season appears to be starting earlier, but there are a few possible factors that could play into this.
For example, there was a late flu season in the southern hemisphere which means there are “more importations” of flu (people bringing it to the UK) towards the start of our season.
Last year, we saw lower immunity to a strain of flu that had changed, which might also play a role this year too.
The UK isn’t alone in witnessing what might be an early flu season. In Japan, “unusually early” flu outbreaks in late summer led to some schools closing.
Eligible people are being urged to get vaccinated for flu now, and not to wait for winter to hit. The school and maternity vaccination programme in England is well underway.
What are the symptoms of flu?
Symptoms of flu typically include: fever, chills, headache, muscle aches and pains, and extreme fatigue, as well as a dry cough, sore throat and stuffy nose.
You can typically tell it apart from a cold because of the fever or body aches (which you don’t typically get with a cold).
Flu can be quite hard to tell apart from Covid-19, which is also currently circulating.
Symptoms of Covid-19 include fever or chills, continuous cough, shortness of breath, tiredness, body aches, headache, sore throat, blocked nose, loss of appetite, nausea, diarrhoea, or change in sense of taste or smell.
Some people are also reporting a hoarse voice or a painful sore throat, a symptom associated with the latest variants of Covid-19 in particular.
Will the flu vaccine work?
Flu vaccines are updated annually as the viruses that are prevalent change year by year.
Some years, ‘drifted’ flu viruses occur, which means the virus that is circulating has continued to evolve and has some genetic changes from the one that was used to make the vaccine.
A recent World Health Organisation (WHO) technical report indicates that one of the flu A(H1N1) viruses that has recently been seen at low levels in Europe and the UK has ‘drifted’ compared to the virus component used in this year’s flu vaccine.
But last year, the UK also saw a ‘drifted’ A(H3N2) flu virus, and experts said the vaccines still gave good protection. Typical vaccine effectiveness is 30-60%, and in 2025, the vaccine’s effectiveness was in this range, rising to 70% effectiveness among children.
Professor Swords said: “Although the weather’s still nice and perhaps people aren’t thinking too much about flu at the moment – please, we are acting early, and I really encourage people to act early because winter is coming. And the pressure [on the NHS] is going to build and rise as temperatures fall.”
NHS England data shows 3.9 million people have already had a flu vaccination this year and 713,000 have had their Covid-19 vaccine.
People aged 75 and over, living in a care home for older adults, or in who are immunosuppressed and aged over six months, are eligible for a free Covid-19 vaccine.
Prof Swords added: “If you’re eligible, get your vaccine now.”
Other ways to prevent the spread of flu and Covid-19 include: staying home if you’re sick, meeting people outdoors or opening windows for fresh air, and practising good hygiene like coughing into the crook of your elbow or a tissue and disposing of it straight away; washing hands regularly with soap; and cleaning surroundings – especially door handles – often.
