A severe strain of flu is thought to be about to infect the UK, raising fears the nation may be set to endure its worst flu season for 50 years.

[Read more: What are the common symptoms of flu and what causes them?]

Over 170,000 cases of flu have been reported in Australia this season, more than two and a half times more than last year.

The strain of flu causing the problems is H3N2, and public health expert Professor Robert Dingwall, from Nottingham Trent University, says it’s “almost inevitable” that the strain will reach the UK this winter. "The reports from Australia suggest the UK might be in for the worst winter flu season for many years,” he stresses.

What’s so bad about Aussie flu?

The number of deaths caused by this season’s flu outbreak in Australia have not yet been released, but it’s thought they’ll be the highest on record.

The reason the H3N2 strain is causing so many problems is linked to flu viruses constantly mutating, meaning vaccines against the illness have to change every season too. The vaccine used in Australia isn’t thought to have worked very well, meaning there were more cases and probably more deaths,

Who’s at risk of Aussie flu?

Flu is a nasty illness, usually with similar symptoms to a cold but much more severe – most sufferers will be bedridden.

It usually only lasts one to two weeks, but can be far more serious in certain at-risk groups who are more likely to develop flu complications such as pneumonia and bronchitis. Those at risk of complications include young children, the over 65s, pregnant women and people with certain health conditions such as asthma, chronic lung disease and heart disease, plus people with a weakened immune system.

Can flu be avoided?

Yes, if you protect yourself with a flu vaccination, wash your hands regularly, use tissues to cover your mouth and nose when you cough or sneeze and clean surfaces to get rid of germs.

Boots Pharmacist Angela Chalmers comments: “It’s not just about protecting yourself from flu this winter but also helping to prevent the spread among family, friends, work colleagues and vulnerable people that you may be caring for. Flu is contagious and it can be passed on through coughing, sneezing or by touching infected surfaces or people. Most flu outbreaks usually happen in late autumn or winter, and, for most people, it's an unpleasant but not a life-threatening condition."

[Read more: Flu jabs: Who can get one on the NHS, will the vaccine give me flu and is flu serious?]

How bad could an outbreak of Aussie flu get in the UK?

Dingwall says the NHS flu vaccination being offered this year is a “reasonable match” for the strain causing problems Down Under, but adds: “NHS and local authority partners should also be reviewing their winter planning to make sure they can cope with the likely extra workload."

However, Public Health England says it can’t be concluded that the UK will definitely be hit by the same strain of flu that occurred in Australia.

Paul Cosford, Public Health England’s medical director, says: “The strains of flu circulating in Australia this past winter have led to a significant increase in cases but it’s too early to know which will be the dominant strains of flu to circulate in England.

“Each year the World Health Organisation reviews the circulating strains of flu and recommends which flu strains should go in the vaccine. It’s really important that as many eligible people as possible get their jab, which is the best way to protect everyone from flu.”