Warnings have now been issued for three strains of flu.
Aussie flu continues to hit the UK, but now there are concerns over French flu and Japanese flu heading here.
In a bid to separate fact from fiction, we've taken a look at the three strains to identify symptoms and establish which is worse.
What is Aussie flu?
Experts in Ireland revealed on December 31 "less than 10 people" have died from the so-called 'Aussie flu' outbreak.
Doctors are now warning children - particularly those aged between five and 14 - could be most at risk.
The Birmingham Mail reports that public health officials are urging people who are eligible for the free flu vaccination should "get it without delay".
Symptoms of Aussie flu:
- Sore throat and cough
- Muscle ache
- Runny nose and sneezing
Symptoms of Aussie flu are similar to those caused by normal flu, but they are more severe.
People should recover from normal flu within a week so, although the cough and fatigue may last longer.
So if you are still really ill after seven days, it is a good indication of something more serious.
Aussie flu can lead to pneumonia and other potentially fatal complications.
This year's flu vaccine has been developed to tackle the main strains which are circulating this season, including H3N2.
A number of strains of the virus, but particularly H3N2, led to Australia's worst flu season for nearly a decade.
The arrival of so-called Aussie flu comes as NHS England urged hospitals to defer pre-planned operations and routine outpatient appointments until the end of the month.
A subtype of influenza A, the bug mainly affects older people, those with long-term health conditions, pregnant women and children.
As flu viruses are constantly mutating, vaccines to protect against the disease have to change each season.
People are asked to take particular caution to spreading germs by washing their hands more often, covering their mouths and noses when they cough, and cleaning surfaces.
Dr Jillian Johnston told the BBC: "Getting the free flu vaccine is the single most important thing you can do to help protect yourself against flu.
"With high levels of flu activity in Australia during their winter, and the potential for similar here, it is more important than ever that everyone who is eligible gets vaccinated.
"We are fortunate to have a more comprehensive flu vaccination programme than Australia or England, but the benefits can only be realised if a high proportion of the groups who can get the vaccine actually take up the offer."
What is Japanese flu?
‘Japanese’ flu, which is contracted and spread particularly by children, has caused experts to urge parents to take up free jabs.
Yamagata flu is less severe but more contagious than Aussie flu.
Experts say this is because very young children are ‘super shedders’, meaning they excrete more of the virus because their immune systems can’t distinguish between what makes them ill and what will kill them.
As a result, children produce a stronger ‘transmission’ of the flu.
Unlike H3N2, protection against Yamagata is not included in the vaccine for over-65s or vulnerable patients, such as those with diabetes or respiratory disease.
Yamagata is a category ‘B’ strain of flu. Complications are less common and most people will recover within a week.
This means it’s less serious than Aussie strain, which is a category ‘A’.
And French flu?
Health workers are being urged to have the jab as the epidemic from across the Channel threatens to hit the UK.
Worryingly, figures show as few as one in three workers have been vaccinated at some hospitals.
NHS trusts are failing to get medical workers to have flu jabs amid the warnings that the French epidemic could spread to Britain.
The paper reports: “It comes amid a deepening NHS winter crisis, with 24 hospital trusts declaring ‘black alerts’ last week, as pressures threatened to overwhelm them, and thousands of patients stuck in ambulances outside hospitals as flu rates soar.”
It has been reported that around one quarter of NHS staff will contract flu during an average winter period.
The Sunday Telegraph reports that figures suggest around half will not show symptoms, which means they could remain in work and spread infections.
Warnings come after a study by Imperial College London which found every 10 per cent increase in NHS vaccination rates was linked with a 10 per cent fall in sickness absence.
What is the difference between flu and a cold?
The symptoms may be similar to a common cold, but flu tends to be more severe.
Flu tends to come on in a few hours, makes you feel exhausted and affects more than the nose and throat alone.
It can also lead to much more serious complications like pneumonia.
How can you protect yourself?
Flu is spread by germs from coughs and sneezes, which can live on hands and surfaces for 24 hours.
The flu vaccine is the best protection we have, though flu strains change so it needs to be done every year.
The flu jab is offered free to adults at risk, over-65s, pregnant women and children at risk aged six months to two years old, and a spray is offered to children up to four.
You can have the jab at your GP and some pharmacies - and it's still not too late to do so. Even though it's best to get vaccinated as soon as the flu vaccine is available, getting the vaccine later can still be helpful.
Even as late as January, there are still a few months left in the flu season, so it's still a good idea to get protected.
Serious side effects of the vaccine are rare.
Anyone can help prevent the virus from spreading by washing their hands regularly, covering their mouth and nose with tissues or a sleeve when they cough or sneeze, and cleaning surfaces they suspect are infected.
How can you treat flu?
Flu usually clears up by itself after around a week, but there are ways you can recover more quickly.
Rest, sleep, keeping warm, taking paracetamol or ibuprofen and drinking lots of water are all recommended.
GPs do not prescribe antibiotics as they will not relieve symptoms or help recovery.
You can seek advice most easily from a pharmacist, and are encouraged not to call 999 or go to A&E unless you develop sudden chest pain, have trouble breathing or start coughing blood.
Patients are advised to only go to their GP if their symptoms fail to improve after seven days, they are a child, over 65, pregnant or have a long-term medical condition or weakened immune system.
What are the experts saying?
Experts have warned that this year's strain of Aussie flu could be more dangerous than the 1968 flu pandemic that killed more than a million worldwide.
Public health expert Professor Robert Dingwall, of Nottingham Trent University, previously told BT.com it's "almost inevitable" that Aussie flu will strike Britain this winter.
He warned: "The reports from Australia suggest the UK might be in for the worst winter flu season for many years."
But Public Health England said that it was not yet known whether the UK would be hit as hard as Australia.