How the flu vaccine works

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Influenza, or simply the flu, is caused by influenza virus. Almost everyone has had the flu at some point high fever, runny nose, sore throat, muscle pains, headaches, coughing, sneezing, and feeling tired it’s terrible.

Good news is that it usually improves in a week, but occasionally someone can go from being completely healthy to being seriously ill requiring hospitalization.

The flu spreads when a sick person sneezes or coughs and sends thousands of virus-containing droplets into the local area.

If they’re lucky, these viruses might land directly on another person’s nose or mouth, but more often they end up landing on nearby objects like a table.

But the flu virus is hardy. It can survive for hours in the environment. To make matters worse, a person may be contagious a day before their symptoms even begin, and up to two weeks afterwards, even after they feel much better!

OK, so if you don’t want to feel terrible with the flu for a week, or get your friends, family and co-workers sick, the most effective way to prevent influenza is through vaccination, which can be done as an injection or nasal spray.

These vaccines usually contain a mix of three weakened or inactivated influenza virus strains that are predicted to be the ones that will dominate for a specific season. 

And because flu viruses mutate rapidly these vaccines are updated twice a year. So how well do they work? Well it depends.

First, high-risk individuals like pregnant women, those with a chronic health condition, or those under 6 months or over 65 years of age are more susceptible to the flu despite being vaccinated.

Second, since the vaccine is based on predictions, some years are better than others. On average, though, the flu vaccine reduces the risk of illness by roughly half from about 10% to about 5% in terms of the likelihood of getting sick over the entire flu season. 

That means that the average person may get the flu about one out of every 10 years without the vaccine and about one out of every 20 years with the vaccine.

So, for any given year, you might decide that your risk of getting the flu is quite low anyways so it’s not worth getting the vaccine. 

But remember, the flu can do more than make you feel terrible, the flu can cause serious injury—even death.

Also, it’s worth remembering that in the 2019 flu season in the Australia—the most recent one where we have complete data — there were 310,011 confirmed cases of Influenza in Australia. The estimated death toll related to the flu was 4,200 in 2019.

Therefore, the more people in a community that are vaccinated against flu, the fewer people will contract and spread the flu.

This protects those that can’t get vaccinated like infants under 6 months old. This is called herd immunity, because the herd is protecting the weakest members.

Yearly flu vaccine is recommended for everyone over six months old, with only a few exceptions. 

Otherwise, since flu season generally begins in Autumn and peaks in Winter, it’s a good idea to get vaccinated by Easter. 

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