What is Influenza?
Influenza is usually a seasonal virus and can cause potentially life threatening respiratory tract symptoms. Every year seasonal influenza causes life threatening infections and death.
Are there different types of Influenza?
Influenza A
Influenza B
Influenza C
Influenza D
Influenza A can be subdivided based on the two different types of proteins found on its surface namely hemagglutinin (H) and neuraminidase (N). Amongst all the subtypes, H1N1 and H3N2 are the most current subtypes of influenza found in humans.
Influenza B has been classified based on an international WHO nomenclature. It normally includes a host origin (swine), geographical origin (Brisbane, Hongkong), strain number and year of discovery of that particular strain etc.
Influenza type C infections generally cause a mild respiratory illness and are not thought to cause epidemics.
Influenza type D viruses primary affect cattle and are not known to infect or cause illness in people.
So why do we need to vaccinate every year, unlike other vaccines?
Normally influenza is a self-limiting condition as we have existing immunity against previous strains of influenza. Our immune system normally reacts to the surface proteins H and N of influenza virus.
However, we need to vaccinate every year because the two surface proteins hemagglutinin (H) and neuraminidase (N) of influenza A virus tend to change every year. Hence Influenza A is considered highly epidemic due to its nature of the mutation in protein structure
Now you wonder what do a triple strain and a quad strain vaccine stand for?
An influenza vaccine normally contains Influenza A subtypes H1N1, H3N2 and one or two types of Influenza B depending on geographical location. A triple strain vaccine (also known as Trivalent) contains H1N1, H3N2 and Influenza B Phuket for southern hemisphere winter season. A trivalent vaccine has been superseded by a quadrivalent vaccine containing all strains of trivalent as well as a Brisbane like influenza B strain.
We are familiar with the type of flu viruses and vaccines now. So why do we need to immunise ourselves against it? Is it worth jabbing a flu shot?
The Department of Health, Australian government quoted that the World Health Organisation estimates that influenza causes 3 to 5 million cases of severe illness, and about 250,000 to 500,000 deaths globally each year. It is a vaccination preventable disease in a developed country like Australia. There is a greater emphasis from our government on flu vaccination each year to prevent morbidity and mortality. The Department of Health is funding flu shots in elevated risk patient under National immunisation program that includes adults 65 years and over, indigenous population with chronic medical conditions and pregnant women.
So why do you trust the effectiveness of flu vaccine? Especially when your mate believes it never worked for him
We will throwback to our discussion about how our immune system reacts to the surface proteins on influenza virus and the tendency of those proteins to change their structure each year and come up as a stranger to our immune system. Hence, when you vaccinate it nearly protects you from an influenza endemic by immunising your body to the mutated strain of Influenza.
However, the efficacy depends on the well being of the person getting vaccinated (age, health and occupation etc) and the similarity between the vaccine and current circulating influenza strain (simple words surface protein structure). So, your mate who believes it never worked might have encountered a different strain of influenza than the strain that he was vaccinated for. Or maybe his weak immune system predisposed him to flu.
Thus remember, before listening to anyone and do a quick check on facts. Vaccines are thoroughly tested for quality and proposed efficacy before reaching doctor’s clinic or your local pharmacy.
Last thing to sum up, so what are the side effects? Are there any contraindications for getting a flu vaccine?
The most common side effects are injection site reactions such as minor bruising, redness, formation of a hard lump. Experiencing flu like symptoms is also common. It can rarely cause tingling and numbness in body and needs medical attention. You may develop an allergic reaction if you are allergic to any of the vaccine components.
It doesn’t have any apparent contraindication unless you are known to be allergic to any of the flu vaccine component including egg protein allergies. If you have reacted to influenza vaccination in past it is contraindicated for you.
If you are still unsure about getting a flu jab, have any concerns or want more information, please consult your healthcare professional or pharmacist. Alternatively comment below to discuss any concerns in Kytos knowledge base community.
