Flu Shot Ingredients: What’s in It and Is It Safe?

We all want to prevent flu, but do you know the best way to prevent it? You get a flu shot. However, several myths are going around about this cold preventive vaccination, even misinformation. One claim often made, that too a dangerous one is from a flu shot you can get infected with the virus. 

The creation of this myth is based on the idea the vaccine contains the influenza virus. Despite that being true, the influenza virus is not live. Rather often the preparation is made from the proteins of the virus or killed virus. There used to create the vaccination to trick the immune system into developing the antibodies (the response) to fight the virus. 

So with 2021 on the way and the influenza season already starting in the Southern hemisphere, due to the present COVID-19 situation, it will be a tad bit more complicated. Simultaneously, the common cold is less this season due to wearing masks, hand sanitization and social distancing. 

But the mortal dangers will be more this time if precaution is not taken against this common yet dominant infection. 

So let’s start with what is in the injection and do away with the misunderstandings about it.

What’s in a flu shot?

In the last half-century, millions have taken injections to prevent influenza, and it has been successful. Extensive researches have been conducted to ensure the safety of these serums. Furthermore, researchers and manufacturers undertake extensive research to update the vaccine since the viruses causing the sickness change. 

CDC (Centres for Disease Control and Prevention) stated that every year, everyone from the age of 6 months onwards with some exceptions, should get the injection. 

In case you are still concerned about the ingredients used in the vials here is the list. 

Apart from the already mentioned dead or weakened virus, the other ingredients are:

  • Formaldehyde: Used in a small proportion to inactivate the influenza virus. According to the CDC, formaldehyde is removed from the vaccine solution before it is packed and dispatched to pharmacies and doctors.
  • Egg Protein: Fertilized chicken eggs are used to grow the viruses; this means there is a small quantity of egg protein present in the serum.
  • Aluminium salts:  Used as adjuvants and in minimal quantity to make the immune system more potent against the virus present in the dose. 
  • Thimerosal: A preservative mainly used in multi-dose vials to stop the contamination. 
  • Gelatine: It acts as a stabilizer and prevents it from getting damaged from freeze-drying or heat from production time to use.
  • Antibiotics: It stops the bacteria from growing in the vials from the time of production to its storage.

Apart from these, the other two ingredients used in the shots are water and sucrose. 

How effective is the flu vaccine?

CDC’s research showed that the shots are effective between 40% and 60% for the overall population, during the season. It is only after 2003; the effective nature of the vaccination was tracked and monitored regularly. Based on this, researchers develop and change vaccination formulas based on the different strains. 

According to experts, there are multiple types of the flu virus, and the two most common are A and B. A is dangerous than B and each category branches out with new occurrence of mutations—scientists and the World Health Organization (WHO), gathers information about the effective nature of the injections across 100 plus countries. 

With the data collated, research is conducted to predict the flu virus dominating the coming season. Depending on that, the vaccines are developed and changed, adjusting to the new strain. This eventually determines the effectiveness of the vaccination. 

As per the CDC report for the year 2019-2020, the vaccination for influenza prevented 7.5 million cases, 3.7 million visits to the doctor for the same reason, 105,000 hospitalizations due to the virus and 6,300 deaths because of the sickens. 

Factors in flu shot effectiveness 

The effectiveness of influenza injections or nasal sprays depends on two primary factors:

  1. The physiognomies of the individual being vaccinated that includes aspects like health, age, any ailments, etc.
  2. The vaccine’s match or similarity with the virus made to protect the community spread. 

At times the preparation does not match the virus; hence the effectiveness of shot can be less. Researchers are always working to determine the flu that will be circulating in the coming year and create a preparation that will be able to combat it.

When the effectiveness of the serum prepared to thwart the virus is studied based on the:

  • Measuring the outcome
  • Population that is studied
  • The season opted to study the vaccine result

Another fact to bear in mind is that influenza vaccination is only effective for that current season. The reason is as mentioned earlier, and the viruses keep mutating and changing constantly.

Benefits of flu vaccines 

Hence, you leave the myths and the misunderstandings of getting the shot behind and go to the doctor get your influenza vaccination. In case, you are still not convinced about getting the injection, or nasal spray here are 5 benefits that might put you on the track. 

  • A lifesaver: It is a preventive that is a lifesaver. Influenza can give rise to severe illnesses and even death. 
  • Better productivity: With the vaccination, you can recuperate at home instead of going to the hospital. Typically 111 million lost working days and about $7 billion in productivity due to the sickness in a year.
  • Mild side-effects: You can get a headache, little temperature and sore throat but only for a day or two while many do not even have that, compared to influenza lasting for a week so two.
  • Community prevention: You help protect the people around you who haven’t or can’t get vaccinated. 
  • Less sick: Even if you get the virus, you will experience milder symptoms due to immunization. 


Getting the immunization prevents yourself and others around you from falling sick due to the virus. With ongoing COVID-19, an individual can contract respiratory infections. The vaccination can help in decreasing such dangers.