Dr Alice McNamara
We have a heightened awareness of Influenza in Australia this year, partly because it’s definitely everywhere, and we’re also getting good at diagnosing it. We also have a very good vaccine and it’s not too late to get it!
While we potentially have not overtaken 2017 yet for our worst ever season for “flu”… we are getting close. And we still have a month of Winter left.
Those of us who work in Hospital Emergency Departments have witnessed what feels like a pandemic, with miserable, aching, coughing people coming in in droves, and Influenza A being the winner so far on our tests in Victoria… 83% in fact according to VIDRL.
All of the States have a medical research body collecting stats on infectious diseases, and the recent observations are saying things like 34,505 cases in Victoria in 2019; 6,418 in NSW last week alone. And hospital admissions are up across the board…
Influenza or ‘The Flu’ is an acute viral illness that mainly affects the respiratory system.
Influenza viruses are classified as type A, B or C, but we only really talk about influenza A and B viruses as they cause the majority of disease in humans.
Type A influenza viruses are further categorised into subtypes according to two kinds of proteins on their surface: haemagglutinin (H) and neuraminidase (N). They are each given a number like H1N1 or H3N2. Type B influenza viruses are typed as Yamagata and Victoria subtypes
Influenza is transmitted or spread easily from person to person, mainly through large particle droplets produced by sneezing and coughing. Droplets containing the influenza virus also settle onto surfaces and can then pass from hands to the nose, mouth or eyes. On hard surfaces the Influenza virus can live for 24 hours. So, wash your hands.
People with influenza can be infectious to others from 24 hours before symptoms start until 1 week after the start of symptoms.
The Influenza virus spreads easily in winter as there are firstly more strains around, and secondly because we are inside more, in close proximity to others. Viruses spread so easily in childcare centres, schools, nursing homes, aeroplanes and between families.
The typical case of the proper “flu” begins with a dry cough then sudden onset of fevers, headaches and muscle aches (myalgias). Nose congestion and fatigue are also common. Children can get gastrointestional pain or vomiting. The Flu can last for 5–8 days with symptoms typically so miserable they result in a week off work, or travel, or training, or anything else important you had planned to do.
The elderly may present with tiredness and confusion, and more often develop respiratory complications requiring hospitalisation. People most at risk are the very old and the very young, with previous respiratory or other disease. The bottom line is cough, plus a fever and muscle aches… that’s the warning sign.
Treatment of influenza is largely symptomatic including bed rest, (SLEEP!), taking simple pain relief for headaches and myalgias such as paracetamol and ibuprofen, and increasing your fluid intake.
Your doctor can prescribe antiviral medications such as oseltamivir (Tamiflu) or zanamivir, which can help reduce the severity and duration of symptoms of influenza. They work by inhibiting the N part of the virus and its replication, stopping the virus from releasing more viruses. To be most effective, Tamiflu needs to be administered within 48 hours of symptom onset. It is not on the PBS so costs about $46 per box. But if you have the actual Influenza virus you are usually willing to try anything.
Please wear a facemask if you head to the doctor or hospital with your flu symptoms!
Vaccination is the only way to specifically prevent Influenza infection and its complications.
There is a different specialised vaccine each year, as the virus mutates often and quickly. It’s been particularly good this year in terms of it has guessed the right Influenza viruses showing up in our lab tests. Most people develop immunity within two to three weeks of vaccination.
The vaccine lasts about three months until its effectiveness starts to wane, which is why flu is particularly contagious. In three months, previous immunity is usually not adequate against disease from a ‘shifted’ strain. This creates the potential for a pandemic.
The concept of “HERD Immunity” early in the season is crucial – The more people who are vaccinated, the less likely that the flu will spread in the community. Vaccinations save lives.
In 2019 many people qualified for a free flu shot; people 65 years and over, pregnant women, those who suffer chronic conditions as well as, for the first time, all Aboriginal and Torres Strait Islander People from 6 months of age.
In 2019 the vaccine for under 65 was QUADRIVALENT (it covered 4 strains). For the over 65s, the ‘high-dose’ Trivalent (3 strain vaccine) was estimated to be approximately 24% more effective.
Influenza virus strains included in the 2019 seasonal influenza vaccines were:
Juniors have a specific vaccine, that should be sourced through your GP. They need 2 x vaccination doses in their first year of the vaccine.
In addition to the vaccine, cough etiquette plays a big role in minimising respiratory droplet spread (such as covering the nose and mouth with a tissue when coughing or sneezing). Also, because the virus can live for 24 hours outside a human, washing hands before eating can help reduce the likelihood of transmitting and contracting the influenza virus. Anyone who is unwell with influenza should stay home from work, school and social gatherings to prevent close contact with and transmission to other people.