News

09-03-2015

Reports in some headlines suggest that this year the influenza season will be severe, particularly following the past two milder seasons.The National Influenza Immunisation Program has been delayed by almost a month to be launched on 20th April, due to supply problems following the reformulation of the vaccine.  Two strain changes were required (as advised by the WHO)  from the vaccine used last season in the northern hemisphere.

Predicting the severity and strains of influenza likely to be most prevalent remains a difficult task, despite authorities using mathematicians,  epidemiologists, social geologists, IT Specialists, physicists and even twitter feeds. Small changes in infection patterns and transmission can cause significant effects. This year the northern hemisphere has had a significant influenza outbreak , as the vaccine used protected only 20-23% of the the H3N2 strain circulating, and resulted in high rates of infection, particularly in the elderly and young children. The vaccine due to be released in Australia has been altered to better protect from the H3N2 strain identified.

Influenza was formally identified in the 1930s and demonstrated in the laboratory and as transmittable between individuals, but the symptoms have been described in writings from ancient Greece. There are three types of flu virus: A,B and C. The most common type is A, which is further divided into the H and N categories according to two proteins on the virus that our bodies respond to - haemaglutinin and neuraminidase. Flu symptoms include fever, headache, cough, sore throat and aches. The symptoms appear quickly and last about seven days, resolving slowly, often with several weeks of fatigue. this differs from a "cold", in which the symptoms tend to come on slowly and recovery often occurs over the next week.

Flu vaccinations are usually 70-80% effective in healthy adults in the years where there is a good match between the vaccine and the commonly circulating strains of flu in circulation. Vaccination is inactive and cannot cause the influenza it is protecting against. Some people can experience side effects, they are usually limited to pain and redness at the injection site, occasionally headaches, fever and fatigue. In the US trials are underway using a live influenza nasal spray for young children. This is not yet available in Australia.

Antiviral medication is available for influenza, but needs to be taken early in the disease to stop the virus multiplying, ideally within 48hrs. The most commonly prescribed medication is Tamiflu, which has been fiercely debated, its safety and efficiency profile has been questioned over several years. In January 2015 another large review was published, ( funded by the manufacturer but independent researchers undertook the meta analysis) finding that the risk of influenza complications such as pneumonia were reduced by the use of Tamiflu in infected adults and the duration of symptoms were reduced by almost 24hrs. There were no benefits of treatment for those who has other viral illnesses than influenza infection. It may therefore have a role for those at high risk of complications from pneumonia infection after influenza such as the elderly.

Despite there being limited other preventive options other than  simple hygiene,  hand washing and avoiding touching your mouth, nose and eyes, and those unwell staying away from work ; the uptake of influenza vaccine is not as high as authorities would like or the statistics support. There are many reasons given and the podcast Freakonomics Radio, January 8th 2015, " Why doesn't everyone get the Flu vaccine?" covers the topic well.

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