The flu is caused by two types of viruses in humans (influenza A and B). After infection, symptoms take between 1 to 3 days to show.
The flu is spread between people through droplets in the air.
Symptoms include: tiredness; fever; chills; headache; cough; sneezing and runny nose; poor appetite; and muscle aches.
Further health problems can develop in some people after infection with influenza including pneumonia, heart, blood system and liver complications, which can lead to death, especially in children and older people and those with pre-existing health conditions.
Flu vaccines do not work well in the elderly and the very young and the vaccine used in 2017 was estimated to be as low as 10% effective, so it makes you wonder how the benefits certainly can outweigh the risks?
Influenza (inactivated) vaccine side-effects
What are the risks from inactivated influenza vaccine?
With any medicine, including vaccines, there is a chance of reactions. These are usually mild and go away on their own, but serious reactions are also possible.
Most people who get a flu shot do not have any problems with it.
Minor problems following a flu shot include:
- soreness, redness, or swelling where the shot was given
- sore, red or itchy eyes
If these problems occur, they usually begin soon after the shot and last 1 or 2 days.
More serious problems following a flu shot can include the following:
- There may be a small increased risk of Guillain-Barré Syndrome (GBS) after inactivated flu vaccine. This risk has been estimated at 1 or 2 additional cases per million people vaccinated.
- Young children who get the flu shot along with pneumococcal vaccine (PCV13), and/or DTaP vaccine at the same time might be slightly more likely to have a seizure caused by fever. Ask your doctor for more information. Tell your doctor if a child who is getting flu vaccine has ever had a seizure.
Problems that could happen after any injected vaccine:
- People sometimes faint after a medical procedure, including vaccination. Sitting or lying down for about 15 minutes can help prevent fainting, and injuries caused by a fall. Tell your doctor if you feel dizzy, or have vision changes or ringing in the ears.
- Some people get severe pain in the shoulder and have difficulty moving the arm where a shot was given. This happens very rarely.
- Any medication can cause a severe allergic reaction. Such reactions from a vaccine are very rare, estimated at about 1 in a million doses, and would happen within a few minutes to a few hours after the vaccination.
As with any medicine, there is a very remote chance of a vaccine causing a serious injury or death.
The safety of vaccines is always being monitored. For more information, visit the vaccine safety web site.
This information is based on the Inactivated Influenza VIS.
Also see this page:
Flu Vaccine studies show very little benefit
NB. Because the vaccines used for Influenza change every year we cannot link to a product information sheet, so we recommend that you look up the name of a vaccine being promoted for flu each year to find the ingredients and side effects etc.