Flu Vaccine: What’s inside?

By Dr. Pallavi Sharma

Table of Contents


The flu, or influenza, is a highly contagious respiratory illness caused by a virus. Symptoms include fever, chills, headaches, extreme fatigue, sore throat, and muscle aches.

The flu can sometimes lead to more serious respiratory illnesses, such as pneumonia. To prevent the flu, the Centers for Disease Control and Prevention (CDC) recommends that everyone six months of age or older get vaccinated each year.

The flu is a serious respiratory illness that can cause severe respiratory illness, including pneumonia. According to the Centers for Disease Control and Prevention (CDC), “Flu activity most commonly peaks in the United States between December and February.”

The flu season marks from early in October and reaches up to February.

Why Do We Need a Flu Vaccine?

Influenza virus type A is causing severe respiratory distress syndrome than type B. It is a contagious disease that spreads from person to person through droplets in the air.

The symptoms of the flu are fever, headache, muscle, and joint aches, sore throat, and extreme fatigue. Influenza pneumonia is a lung infection that can be deadly if not treated promptly.

Pneumonia symptoms include chest pain or pressure, shortness of breath with breathing or coughing, rapid breathing or trouble breathing at all, and low energy level.

The flu is a serious illness that can lead to hospitalization or death, particularly in high-risk groups. Every year, 5 to 20% of the US population gets the flu, and over 200,000 people are hospitalized for flu-related complications.

Flu can be prevented by getting vaccinated every year before the onset of winter and taking care to wash your hands frequently and avoiding contact with people who are sick.

Even though the flu is a serious illness, many people do not get vaccinated against it. According to the Centers for Disease Control and Prevention (CDC), only about 40% of adults in the United States Submit flu vaccine each year.

This is partly because some people think that the flu is not as serious as it is. Others are simply uninterested in health risks.

What is the Flu Vaccine Made of?

The flu vaccine is made up of three ingredients: an antigen, an adjuvant, and other substances. The antigen is the virus that is being protected against. The adjuvant is a substance that helps the vaccine stick to the cells of the person receiving the vaccine.

Viral Particle

The vaccine’s active ingredients are a weakened or killed form of the virus and sometimes inactivated parts of the virus that cause pneumonia.

Most flu vaccines have inactive particles or killed viruses themselves, while nasal sprays have a weak live form of the virus.


The inactive ingredient, like thimerosal, is a preservative that helps to keep the vaccine effective and away from contamination by bacteria or funguses.

Preservatives are present in multidose vials more than in single-dose vials. So if you have doubts about allergies, you can get an egg-free, preservative-free single-dose vaccine.


There are egg-based proteins made into vials of flu vaccines and synthetic proteins made into viral vaccines.

The CDC says that the flu shot ingredient egg protein can cause an allergic reaction in people who are allergic to eggs.

Flucelvax is a non-egg-based flu vaccine.

A new vaccine that protects against four strains of flu, the Flucelvax Quadrivalent flu vaccine, has been approved for use in the United States.

The vaccine is made up of two influenzas A viruses and two influenza B viruses. It is designed to protect against four strains of flu, including H1N1, H3N2, and two types of B virus.

The vaccine was approved by the U.S. Food and Drug Administration (FDA) in October 2018.

Your body produces antibodies that protect you from future infections about two weeks from the time you receive the shot.

Stabilizing Agent

Stabilizers are to protect vaccines from temperature shifts or other weather conditions once they are manufactured.

It can be either sugar or gelatin.


The vaccine contains a chemical called formaldehyde.

Formaldehyde is a chemical that is used in several industries, including the production of vaccines.

The vaccine contains a small amount of formaldehyde, which helps to prevent the growth of bacteria that may contaminate it.

In most cases, formaldehyde is not an issue for people with healthy immune systems.

The presence of this chemical in flu vaccines has been controversial for some time now, and there are many misconceptions about it.

It has been found that the amount present in these vaccines is too small to be harmful to humans, and it cannot cause cancer or other harmful effects on its own.

Other Substances

Inactive ingredients, such as antibiotics (such as gentamicin and neomycin), and other chemicals also help with vaccine production.

Other ingredients are not necessary for the vaccine to work properly. But they may be used to stabilize the vaccine or to make it easier to produce in large quantities.

Protect from bacterial overgrowth with antibiotics (gentamicin and neomycin).

Polysorbate 80: This is an emulsifier. This will help to keep the contents of the vaccine soluble.

Aluminum: It increases the effectiveness of the vaccine. It helps your immune system identify the vaccine early.

Side Effects of Flu Vaccines

The flu vaccine is safe for most people, but there are a few side effects that can occur.

These side effects include

  • Soreness
  • Redness
  • Swelling at the injection site
  • Headache
  • Fever
  • Muscle aches

These symptoms may disappear without any treatment. But some mistake these symptoms for the flu. It is not.

Some people may experience an allergic reaction to the flu vaccine. It is less than 1% in incidence. This is due to getting an egg-based protein vaccine or if you have an allergy to an ingredient in the vaccine.

It is important to notify your doctor regarding your allergies and previous vaccine experience before taking the flu vaccine.

There are a few reports of Guillain-Barre Syndrome with the flu shot, which has caused bilateral lower limb weakness and numbness. But this incidence is very low, at around 1–2 cases per year worldwide (0.0001%).

There is a common misconception that the flu shot can give you the flu. However, this is not the case. The flu shot cannot give you the flu because it is made with dead viruses.

The Advantages of Flu Vaccination

There are many advantages to the flu vaccine.

The first advantage is that it reduces the severity of the symptoms.

It also reduces the duration of illness and it prevents infection.

Another advantage is that it can be given to people who are at higher risk for complications from influenza, such as pregnant women, children under two years of age, and people over 65 years old with certain chronic diseases.

You’ll have to Submit flu shot if you’re going to school.

It’s one of the few things that all kids have to do, but some parents think it’s a waste of time and money. They say that the flu shot doesn’t work anyway and that it makes their kids sick anyway.

But here’s an important fact: the flu shot does work! It protects you from getting a cough and fever, which is one of the most serious childhood diseases out there.

If you do get sick from the flu, it is worse than getting sick from any other illness.

So don’t let people tell you that the flu shot doesn’t work; it does! And if you’re worried about side effects like fever or headache, just ask your doctor about taking an antipyretic instead.

When to Visit the Doctor

There are many factors that influence when an influenza outbreak takes place. Many of these factors include how many people have immunity suppressed due to other health conditions and how crowded the environment is.

These factors make it easier for an outbreak to take place in a busy environment where many people are exposed to coughs propagating the flu. In these cases, it’s easy for many people to catch the flu at once.

When an outbreak does take place, it’s important to remain vigilant so you can prevent the further spread of the disease.

You need the flu vaccine if your immune system is compromised, you have underlying diseases, or you are over the age of 65. It’s because they are at risk of getting pneumonia and other complications.

Once you have got the flu, if you are having the following symptoms, you need special care from a doctor.

  • High fever (> 104 F) with neck stiffness, headache, and light sensitivity (meningitis)
  • Cough with pink-colored sputum and chest pain (pneumonia)
  • Excessive vomiting, reduced urine flow, and faintishness (dehydration).

TeleHealthDoc articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Dr. Pallavi Sharma

Dr. Pallavi Sharma is one of Melbourne’s best, well respected cosmetic doctors and aims to provide longstanding anti-aging benefits for her clients. With over 11 years experience in Performing cosmetic procedures, Dr. Sharma has lectured medical professionals regarding cosmetic treatments and is heavily involved in providing up to date cosmetic treatments to her clients and friends.
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