All you need to know about the flu shot

Flu season is here and it’s here in full force. If your doctor hasn’t yet asked you to get a flu shot, they may soon. The World Health Organization (WHO) recommends mandatory administration of flu shots to children, pregnant women, the sick and the elderly, every year. And while the rest of us like getting days off from work occasionally, none of us wants to spend them in bed, coughing and sneezing.   Which brings us to the question - have you ever considered getting the flu shot? If yes, did you also wonder why you have to go through these expensive shots over and again? Shouldn’t getting it just once be enough?   [caption id=“attachment_7644981” align=“alignleft” width=“380”]  Representational image. Image source: Getty Images.[/caption] Well, experts say that the influenza virus — the microorganisms that cause the flu — is smart and keeps on changing its genetic material every year. Every new change makes the previous vaccine useless. To be safe from the latest version of the virus, you would have to take the new vaccine. Here is a primer on some of the most common types of flu vaccines along with some of the key facts about this year’s flu shots.  

Influenza/flu

Seasonal influenza is one of the most common respiratory infections in the world. It causes sudden onset fever along with cough, muscle pain, runny nose, sore throat and headache that can last up to two weeks. In most cases, the condition subsides on its own; however, in children, the elderly and the sick, it can turn severe and life-threatening.   According to WHO reports, three million to five million people get severe influenza every year. The disease contributes to 290,000 to 650,000 deaths annually. There are four different types of influenza virus - A, B, C and D. Out of these, only influenza A and B cause serious illness. Your yearly flu shot targets both these viruses at once.   This is where it gets a little complicated. Influenza A has various subtypes — H1N1 and H3N1 being the current ones in circulation — and Influenza B has two lineages that differ in the molecular structure of a surface protein. Every year, WHO observes and finds the most prevalent type of influenza A and B and composes a different vaccine.   Currently, a trivalent influenza vaccine is given in most countries. These protect you from two subtypes of influenza A and one of the two types of influenza B. However, a quadrivalent vaccine - protecting you from both the types of influenza B is also used in some countries.

Two types of vaccines

There are two different types of influenza vaccines. First, the live attenuated one which contains a weakened version of the live virus (which can’t cause the flu by itself) and is given as an injection in the muscles to anybody above six years of age. Second, the inactivated one, which has the inactivated influenza virus that is unable to cause infection but can generate immunity. It is given as a nasal spray (single dose) to healthy people within the age group of two to 49 years and is not recommended for pregnant women or those with chronic diseases. If a child — between two and eight years — was not vaccinated in the previous flu season, the doctor would likely suggest two doses of this vaccine, to be given four weeks apart.

Flu shot in 2019

The trivalent flu shot 2019 contains:

• Influenza A/Brisbane/02/2018 (H1N1)pdm09-like virus
• Influenza A/Kansas/14/2017 (H3N2)-like virus  
• Influenza B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage)

The quadrivalent vaccine, along with the above three also contains Influenza B/Phuket/3073/2013-like virus (B/Yamagata/16/88 lineage).   Experts suggest that it is best to take the vaccine two weeks before flu season starts since it takes this much time for your body to build antibodies against the virus. If you get immunised earlier than this, the vaccine would slowly lose its efficacy and would not provide as much protection.

Side effects of flu vaccine

Like most vaccines, the flu vaccine also has some side effects. For starters, you may feel muscle ache for a few days after you get the shot. Other possible side effects include headache, fever and nausea. In children, the side effects would be more prominent. An allergic reaction to the flu shot is rare - if it does happen, it would happen within minutes of getting the shot. Symptoms of an allergic reaction include breathlessness, hives, wheezing, swelling around lips or eyes, dizziness and fast heartbeat. Contact your doctor immediately if you get any of the severe symptoms. Health articles in Firstpost are written by myUpchar.com, India’s first and biggest resource for verified medical information. At myUpchar, researchers and journalists work with doctors to bring you information on all things health. For more information, please read our article on   Flu: Symptoms, Causes, Treatment_._