Influenza

the flu shot can't give you the flu

A personal story

Here is Kelly’s story of influenza; how it took the life of her mother when she was a baby, how it affected her when she caught it herself a few years ago, and how it is still impacting on her life today.

Summary

People have more questions and concerns about influenza and its vaccine than almost any other vaccine preventable disease. Here is a brief video summarising the facts;

And here’s some more details;

The disease:

  1. Can and does cause serious disease and even death in otherwise healthy, fit, young people.
  2. Is often more serious in those who have underlying disease, are pregnant or are at the extremes of age, but it can be fatal even in those with no other medical conditions.
  3. Never having got influenza before does not protect you from getting it in the future.
  4. Not getting colds makes no difference to your chances of getting influenza, they are totally different diseases.
  5. A cold (aches and pains, fatigue, headache, runny nose) that lasts for a few days, no matter how unpleasant, is NOT influenza. Gastroenteritis isn’t ‘stomach flu’ either.

The vaccine:

  1. It is physically impossible for the influenza vaccine available in Australia to cause influenza, it doesn’t contain any live virus. To repeat; the flu shot CANNOT give you the flu.
  2. Whilst not 100% effective, the protection it offers is better than nothing, which is what you get if you don’t get vaccinated. Less than 100% does not equal 0%!
  3. Most years the flu vaccine offers otherwise healthy people a 50-60% reduction in risk of getting the disease, and a 70-80% reduction in risk of hospitalisation/life threatening disease.
  4. Even if it doesn’t stop the disease altogether it might stop you dying from it.
  5. You need a different vaccine every year because the virus changes, not because the vaccine is useless.
  6. No diet, food, exercise regime, or lifestyle factor can offer you specific protection from the disease.
  7. The influenza vaccine will not protect you from a cold or other respiratory virus/infection. It will, however, protect you from influenza.
  8. It HAS been tested in pregnancy, and it is both safe and effective for both mother and baby, and recommended as pregnancy is a risk factor for serious and life threatening disease. Getting an influenza vaccine when pregnant will also protect the new baby for about the first 6 months of life.

The full story: facts about influenza, the disease and how to prevent it

The disease

  • Influenza is a contagious viral disease that affects many millions of people a year.
  • It is estimated that there are an average about 13 500 hospitalisations due to influenza per year in Australia and around 3000 deaths per year in Australians aged over 50 years old.
  • Influenza causes a wide spectrum of disease, often manifesting with high fevers, muscle aches and pains, headaches, a cough and runny nose. It can also cause severe respiratory illness with multisystem complications and death from primary viral or secondary bacterial pneumonia.
  • More severe disease commonly occurs in those with underlying diseases such as asthma, emphysema, obesity, heart disease, diabetes, in the elderly, in those of Aboriginal and Torres Strait Island heritage, and in pregnant women. However, influenza can be fatal even in the young, fit and healthy with no underlying medical problems.
  • In addition to the loss of life, suffering, and hospitalisation, annual influenza outbreaks represent a significant healthcare burden and cost to industry and to the individual. One study found that in Australia influenza required over 300,00 GP consultations a year, costs the Australian health care system at least $85m annually, and that 1.5 million work days are lost annually.

NRVS poster asthma

 The virus

  • There are various types of influenza virus. Broadly they are classified into types A, B and C (with A and B more commonly involved in human disease).
  • Influenza viruses possess two surface glycoprotein antigens: the haemagglutinin (H), which is involved in cell attachment during infection, and the neuraminidase (N), which facilitates the release of newly synthesised virus from the cell. Influenza A viruses can be classified into subtypes based on differences in these surface antigens.
  • Both influenza A and influenza B viruses undergo frequent changes in their surface H and N antigens. This results in a phenomena known as ‘antigenic drift’, which means that from year to year the influenza virus is subtly different. It is because of this change in antigenic appearance that the virus can evade an immune system that has been previously exposed through disease or vaccination, it is for this reason that the flu vaccine is subtly different every year, and it is for this reason that yearly vaccinations are advocated. ie you need a new vaccine every year, not because the flu vaccine doesn’t work or wears off, but because the virus changes every year.
  • Under the right circumstances, a whole new subtype of influenza can emerge. When this type of major change in the influenza virus occurs, it is known as ‘antigenic shift’. Because the immune system has never been exposed to viruses of this new subtype before, and has no ability to recognise it and combat it, the virus tends to cause very severe infections with a high mortality rate. This kind of change can lead to influenza pandemics.
  • The word pandemic (from the Greek language pan meaning ‘all’ and demos meaning ‘people’) is used to describe an epidemic that affects the whole population across every continent.
  • An influenza pandemic occurs when:
    • a new subtype of influenza virus emerges in humans to which most people have not been previously exposed and are, therefore, highly susceptible
    • the virus causes serious disease in humans
    • the virus is easily and rapidly spread between humans, infecting large numbers of people worldwide and causing many deaths.

 How contagious is it?

  • In most years, minor or major epidemics of type A or type B influenza occur, usually during the winter months in temperate regions.
  • The severity of ‘flu seasons’ vary from year to year depending on the circulating virus and the susceptibility of the population. For example, there were over 10 000 cases in Australia in the first half of 2011, compared with approximately 1570 for the same period in 2010.
  • It is well recognised that this is a substantial underestimate of the impact of influenza. Each year during flu season mortality rises, especially among the elderly and people with chronic diseases, and there are increased rates of hospitalisation for pneumonia, and exacerbation of chronic diseases such as asthma. These patients do not end up in the statistics for influenza as testing is not done and a formal diagnosis often not made, but it is well recognised that influenza plays a major role.
  • During regular seasonal influenza, the attack rate within the community is generally 5-10% (ie 5-10% of the population catch it when it is ‘going round’.). During pandemic years the attack rate can be as high as 20-25% and will be 2-3 times higher for close household contacts.
  • Three pandemics were recognised in the 20th century, in 1918 (H1N1), 1957 (H2N2) and 1968 (H3N2). Each of these pandemic strains replaced the previously circulating influenza A subtype and went on to circulate as seasonal influenza. These pandemics were associated with a higher than normal attack rate, and a higher than normal complication rate, particularly in otherwise fit and healthy young people.
  • The influenza pandemic of 1918-1919 killed more people than World War I, it is not certain how many people died, but estimates are as high as 50-100 million people. It is thought about 25% of the worlds population was infected.

 The vaccine

never get it

  • The composition of vaccines for use in Australia is determined annually by the Australian Influenza Vaccine Committee.
  • Influenza vaccines normally contain three recommended strains of virus, two influenza A subtypes and influenza B, representing currently circulating viruses. In 2016, in addition to the trivalent vaccine (protecting against three strains), there is also a quadrivalent vaccine available in Australia, covering 4 strains.
  • Influenza vaccines currently available in Australia are either split virion or subunit vaccines. In some other countries such as the USA and the UK there is also a live attenuated version available as a nasal spray. Split virion vaccines consist of broken up fragments of influenza virus particles, whereas subunit vaccines contain various antigens from the viral particle. In other words, the vaccines available in Australia do NOT contain live virus particles, and as such it is utterly impossible for them to cause influenza themselves.
  • The effectiveness of the influenza vaccine varies from year to year, depending on how closely matched the vaccine is to the circulating strains, how virulent the circulating strain is, and of course the immunocompetence of the person receiving the vaccine. On average, however, the influenza vaccine is 60-85% effective at preventing disease in young children, and 60% effective in adults. For example, a recent study showed that flu vaccine reduced a child’s risk of flu-related pediatric intensive care unit (PICU) admission by 74% during flu seasons from 2010-2012.
  • Influenza vaccines are recommended for all people over the age of 6 months who wish to reduce their risk of contracting influenza.

Healthy

  • There are certain groups of people who really should be vaccinated each year. This includes the following groups [* indicates that in Australia the influenza vaccine is funded for this group via the National ImmunisationProgram (NIP)]:
    • adults aged ≥65 years*
    • Aboriginal and Torres Strait Islander people aged ≥15 years*
    • pregnant women*
    • immunocompromised persons*
    • individuals aged ≥6 months with specified medical conditions that put them at increased risk of influenza complications*
      • High risk background medical conditions include chronic respiratory and cardiac disease (such as asthma or coronary artery disease), chronic neurological conditions (such as spinal cord injury or multiple sclerosis), and diabetes.
  • The following groups of people can potentially transmit influenza to persons at increased risk of complications from influenza infection and vaccination of these groups is therefore recommended to protect those at risk:
    • all healthcare providers (particularly those of immunocompromised patients)
    • staff (or volunteers) working in nursing homes
    • staff (or volunteers) working in long-term care facilities
    • household contacts (including children ≥6 months of age) of those in high-risk groups, including providers of home care to persons at risk of high influenza morbidity
    • staff working in early childhood education and care
    • staff (or volunteers) providing care to homeless people.

 

  • Adverse events to any vaccination can and do occur. However, these are usually very minor, or extremely rare. 1-10% of people suffer from some fever, malaise and myalgia which may mimic influenza infection, but this is mild and shortlived. It is not possible for the vaccine to cause the disease (see below for an explanation why). In children <5 years of age, these side effects may be more pronounced. A sore arm (with redness and swelling) can occur at the injection site, however, most patients report that these events are transient and resolve fully within a few days.
  • In 2010, an excess of fever and febrile convulsions following influenza vaccination was reported in children aged <5 years, particularly children aged <3 years. This was associated only with one manufacturer’s vaccine (Fluvax and Fluvax Junior, CSL Limited) and this vaccine is no longer registered for use in children aged <5 years and is not recommended for administration in children aged <10 years.
  • Immediate adverse events (such as hives, angioedema or anaphylaxis) are a rare consequence of influenza vaccination and probably represent an allergic response to egg protein. However even a history of anaphylaxis with eggs is not an absolute contraindication to the vaccination, but should be done in consultation with a medical provider.
  • A small increased risk of Guillain-Barre syndrome (transient paralysis) was associated historically with one influenza vaccine in the United States in 1976, but, since then, close surveillance has shown that GBS occurs at a very low rate of up to 1 in 1 million doses of influenza vaccine, and is more common after influenza itself.

Here is a simple explanation of why we are so sure you cannot get influenza from the influenza vaccine.

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And, finally, we are ‪#‎flufighters‬, are you?

The NRVS admin team make informed choices about vaccinations. We know the risks of influenza, and we know that getting a flu shot every year is the safest and most effective way to protect ourselves, our families, and our community from the disease. So here we are, showing off last years protection (April, 2016).

flufightersadmin

 

References and further reading:

 

Page reviewed August 2017.
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