As soon as autumn arrives, you can hear the word flu (a shortened version of the term influenza) being talked about everywhere. But, do you know what causes influenza? What’s in the vaccine? How it works? And whether it’s right for you? Dr Jui Tham, Chief Medical Officer at rt health fund has the answers …
The influenza virus explained
Influenza is an infection caused by a number of different viruses – tiny organisms that can invade living things – plants, animals (including other microorganisms) and humans.
Infection spreads via droplets of air-borne moisture – one sneeze can project 100,000 particles into the air. And, in just 12 hours, one influenza virus can invade and multiply through a million cells in your nose and throat. If they reach the lungs, they can trigger problems like bronchitis and pneumonia. Every year in Australia, influenza causes about 18,000 hospitalisations and 300,000 GP consultations[i]. It can be a serious condition for the very young and the elderly, for whom it can be fatal. For the majority of the population who are generally reasonably healthy, it isn’t fatal but can be very debilitating.
More about the viruses
The tiny microorganisms that are influenza viruses can only replicate inside a living organism so they’re always looking for a way to get inside you. When they do, viral cells take charge of your body cells making them produce more viral particles, turning your cells into a sort of influenza factory. And, as they increase in number, symptoms are triggered – fever, aching, shivering and more.
One of the ways your body’s immune system defends against infection, after detecting microorganism invaders, is by fighting them by producing very specific antibodies, disease-fighting soldiers. After fighting that particular invader, the blueprint to overcome it is retained. That way, should your body encounter that very same organism, it can rapidly produce and deploy the soldiers needed to destroy the particular invader and protect the body from infection.
The trouble is, viruses can easily change their format slightly (mutate). This tiny mutation means that it becomes an organism that the body hasn’t encountered. So, a whole new blueprint for the infection fighter has to be made. And this takes time.
What’s in the vaccination?
Because viruses mutate easily, a new vaccine is needed every year – last year’s vaccination probably won’t protect you from this year’s outbreak.
The vaccination contains three strains of the viruses that have caused the most illness in the northern hemisphere the season before.
The vaccine contains dead viruses – they don’t need to be alive to trigger your body to produce antibodies to them. So, if you were to encounter any of the three strains contained in the vaccine, your immune system can act rapidly.
Will the vaccine give me influenza?
Because the vaccine contains dead viruses, it can’t trigger influenza. Sometimes people feel ill after an influenza vaccination but this is more likely to be due to an unconnected infection such as a cold. It is still possible for you to catch an influenza virus after vaccination – there are many strains of influenza virus around and the vaccination only protects you against the three most common strains.
In fact, there are so many different types of influenza virus that it isn’t possible to mass-produce a vaccine to protect against them all. But what the vaccine does do is alert your body to the threat of it without the virus being able to reproduce and cause symptoms. Even so, there might be a little soreness around the injection site and, rarely, a slight temperature and aching muscles for a couple of days afterwards.
Who needs it?
Experts recommend that certain people get vaccinated against influenza because if they were to catch it they may pass it onto vulnerable people or because they may be vulnerable themselves.
Vaccination is recommended for anyone over six months who wants to be protected against influenza. And it is free for:
- People over 65 years
- Aboriginal and Torres Strait Islander people from 15 years of age
- Aboriginal and Torres Strait Islander children aged from six months to less than five years
- Pregnant women
- Infants aged six months or older with heart disease, asthma, chronic lung disease, diseases of the nervous system, impaired immunity, diabetes or infants who have had a chronic illness requiring medical follow-up or hospitalisation in the past year
- Children aged six months to 10 years who are on long-term aspirin therapy
- People who live or work in nursing homes/other long-term care facilities and people who are homeless.
If you don’t fall into these at-risk groups, you can still go along and get vaccinated at your GP clinic – some pharmacies also provide this service and it will cost you around $10.
When should you have it?
It’s best to be vaccinated in autumn before winter comes to allow you time to build immunity (it can take three weeks after immunisation to do this). The vaccine is released in March/April and the influenza season lasts until August/September.
Is it safe?
Talk to your doctor if you have an egg allergy, as the vaccine might contain traces of egg. And don’t have a vaccination if you have a cold or influenza because of the slight chance of fever. Otherwise, the influenza vaccine is considered safe.
We’ve known for a long time that exercise can help to boost mood and build strength and it may even boost resistance to infection. Researchers at the University of Sydney are studying whether exercising before having an influenza vaccine could improve its effectiveness[ii]. The researchers say that although we know that regular exercise activates the immune system, it may also improve the body’s response to the vaccine.
To find out more, talk to your GP or go to www.immunise.health.gov.au.
[i] Influenza Specialist Group. Influenza Fast Facts. http://www.isg.org.au/index.php/clinical-information/influenza-fast-facts-/
[ii] University of Sydney. Flu shots boosted by exercise. http://sydney.edu.au/news/84.html?newsstoryid=11426