Recently released data by the HSE shows that this year’s flu season has been particularly rough, and there are a lot of questions floating around about the so-called “Aussie Flu Outbreak”.

The “flu” is an infection caused by the influenza virus. Symptoms include a fever of 38C, chesty cough, headache, muscle ache, and fatigue. A visit to the doctor is not required, unless there are secondary complications, or the individual is part of an at-risk group (Over 65s, young children, people who already have other medical issues), as these individuals have weaker immune systems and therefore are at a higher chance of developing complications. The most common complication is a bacterial infection that occurs due to the lowered immune defences of the flu patient.

There are many different strains of the influenza and different ones circulate each year. The Centre for Disease Control and Prevention (known as the CDC) release a recommended vaccine against what is predicted to be the most likely strains to circulate each year. Influenza viruses mutate rapidly, so administering a new flu vaccine each year provides the best protection.

Flu strains may be categorised by origin and by whether they are caused by influenza virus A, B or C. The trivalent (or, ‘containing three strains’) 2017/18 flu vaccine, which is the most common in Europe, contains protection against three strains of the influenza virus, an A/Michigan-like virus; an A/Hong Kong-like virus; and a B/Brisbane- like virus. This Brisbane virus may be the root of the Australian association with this year’s outbreak. The moniker is misplaced, however, as the strain that has been affecting most the Irish people this year is a B/Yamagata-like virus. The quadrivalent (‘containing four strains’) flu vaccine contains protection for this strain, too, but the trivalent version was more commonly administered.

This flu season has indeed been more severe than usual, both in terms of numbers of infected individuals and the severity of the infections. In Ireland, the number of patients with influenza-like illnesses has been above the baseline threshold for 5 consecutive weeks and above medium threshold for 2 consecutive weeks, at the time of writing. This higher level has been seen across all HSE areas, with the level being described as “widespread”. GP out-of-hours calls that mention influenza-like symptoms are the highest they’ve been since 2010/11 – during the swine flu outbreak. There have been 463 hospitalizations related to the flu in just the first two weeks of 2018.

People can mistake a bad cold for the flu, but there are many differences between the two. The common cold develops gradually, is not severe, and mainly affects the nose and throat. Flu symptoms arise suddenly, include fever and muscle ache, stopping you from doing normal daily activities.

Influenza viruses are spread easily, as an individual can be infectious a day or two before symptoms arise. The virus can be spread in airborne water droplets from coughs and sneezes. These droplets can be inhaled directly by another person or picked up by touching common surfaces. While the virus is not dangerous for most people, it is still unpleasant. For that reason and for the sake of the more vulnerable members of our society, flu vaccines exist. Taking precautions such as vaccination, maintaining good hygiene practices, and avoiding large groups of people greatly decreases your risk of flu, outbreak or no.

Danielle O’Rourke – Science Writer