Flu season is well and truly upon us for 2019. With thousands of cases already seen this year, there is a lot of concern around the ‘flu season ahead. Let’s look at some of the facts.
Influenza illness – or the flu – is a caused by the influenza virus. It often comes on rapidly, with a high fever, chills, muscle aches, tiredness and a dry cough. These symptoms get worse over the first few days.
Most people will get better without medical care, but some are at higher risk of dangerous complications. This includes pregnant women, children, those aged over 65, people with chronic diseases and Aboriginal and Torres Strait Islander peoples.
What was last year’s flu season like?
Actually, the 2018 influenza season was pretty mild. The season started late, comparatively few cases were seen in GP clinics and hospitals, it had a low impact on workplaces and hospitals, and it caused a moderate level of illness.
This contrasts with 2017, which was a severe year resulting in at least 1255 deaths.
It’s too early to assess the 2019 season as this is usually done after the flu season ends. But GPs are seeing more flu-like illness for this time of year than in previous years.
Why is it so hard to predict?
Part of the problem with predicting the influenza season is that we talk about one season, but there are four distinct influenza virus types. Influenza A is further subdivided into two subtypes: H1N1 and H3N2. Influenza type B is further subdivided into B/Victoria and B/Yamagata.
All four of these viruses are covered by the four-strain influenza vaccine that is available for Australians aged under 65 years.
For adults aged 65 years and older, an enhanced vaccine is available, free of charge, that contains the two influenza A subtypes and one influenza B. This year the B strain is B/Yamagata, because in 2018 we saw many more B/Yamagata than B/Victoria viruses.
Flu viruses are continually mutating in nature, so any immunity acquired from a previous infection or vaccine may provide little protection against the viruses that will circulate in the next season.
There is also little cross-immunity. Infection with A(H1N1), for example, won’t necessarily protect you against A(H3N2). It is even possible, though unlikely, to be infected with two viruses at the same time or in close succession.
In Australia, one of the influenza A viruses will typically dominate. It is rare for influenza B to dominate. It is even rarer for both lineages to circulate at the same time, but it happened in 2015.
The burden of each of these viruses also varies. Children may be more susceptible to influenza B infections than adults, while the elderly are relatively less susceptible to infection with A(H1N1) but are more vulnerable to A(H3N2) infections.
Although deaths have been associated with all four viruses, A(H3N2) generally causes more deaths than the others, particularly among the elderly. We usually don’t know exactly what influenza virus has caused the problem as testing can be expensive, inconvenient and often does not alter the course of the disease.
Who should get a flu vaccine done?
Everyone is encouraged to get a flu jab. As the years have gone on, the vaccine has become much more effective which a much lower risk of side effects, so the risk / benefit ratio is almost always in favour of having it done. The flu jab cannot give you the flu!
Some people are at more risk than others. These populations can usually get a free flu vaccine:
- pregnant women (at any stage of pregnancy)
- children aged 6 months to less than 5 years (learn more about the flu vaccine for children)
- people 65 years and older
- Aboriginal people 6 months and older
- People 6 months and older with medical conditions that put them at risk of severe flu, including:
- heart disease
- kidney disease
- chronic respiratory conditions
- chronic illnesses that required regular medical attention or hospitalisation in the previous year
- chronic neurological conditions
- impaired immunity
- children aged 6 months to 10 years receiving long-term aspirin therapy.
Who should NOT get a flu jab done:
- Less than 6 months of age
- Acutely unwell with a fever of over 38.5C
- Life threatening allergic reactions to flu jab or its components, such as egg or gelatin
- Past history of Guillain-Barre syndrome, a rare immune system disorder
- Some patients on chemotherapy – check with specialist
This year at Azure Medical we have done A LOT of flu jabs, which is great. Stock has been limited at times, but we are getting new stock frequently, so please call us if you still need to get your flu jab done.
Article taken from, credited to and adapted from https://www1.racgp.org.au/newsgp/clinical/flu-season-2019-looking-ahead