iCliniq logo

Ask a Doctor Online Now

HomeHealth articlesinfluenza vaccineWhat Are Seasonal Influenza Vaccines?

Seasonal Influenza Vaccination - Types and Benefits

Verified dataVerified data

4 min read


Seasonal influenza, or flu, is a common infection seen in all age groups. The article below describes the various features of seasonal influenza vaccination.

Written by

Dr. Neha Rani

Medically reviewed by

Dr. Basti Bharatesh Devendra

Published At April 20, 2023
Reviewed AtMay 9, 2024


Seasonal influenza is a disease that can be prevented by vaccination, and the best way to prevent influenza is to get vaccinated every year. It is important to vaccinate individuals who are at greater risk of getting infected with the influenza virus, like elderly people, pregnant women, children between the ages of six and 60 months, people with chronic health conditions, and healthcare professionals.

What Are the Types of Influenza Viruses?

Seasonal influenza is caused by influenza viruses all across the world. It causes respiratory infections in humans. There are four varieties of seasonal influenza viruses. The subtypes are A, B, C, and D. The influenza A and B viruses spread and results in seasonal epidemics

  • Influenza Type A Virus - They are further categorized based on the combination of neuraminidase (NA) which is a protein and hemagglutinin (HA) on the surface of the virus. The influenza viruses of subtypes A (H1N1) and A (H3N2) are currently present in humans. The A (H1N1) virus is also referred to as A (H1N1) pdm09 because it started the pandemic in 2009 and then uprooted the seasonal A (H1N1) virus that had been in circulation before 2009. The only influenza viruses known to have caused pandemics are type A viruses.

  • Influenza Type B Virus - They cannot be categorized into subtypes but can be divided into lineages. There are two lineages of influenza type B viruses that are currently in circulation: B/Yamagata and B/Victoria.

  • Influenza Type C Virus - It is less frequently found and typically only results in minor infections and hence is not of great public health concern.

  • Influenza Type D Virus - It mainly affects cattle and is not known to infect or afflict humans.

What Exactly Is a Flu Shot?

Flu shots or influenza vaccines provides defense against four influenza viruses, which, according to research, are most commonly present during the upcoming season. The majority of flu shots are administered with a needle, typically in the arm, but there is also a nasal spray vaccine available.

What Are the Various Types of Flu Vaccines Available?

There are numerous flu vaccines from various flu vaccine manufacturers available in the market and recommended for use. However, the most crucial thing is that everyone aged six months and older receive an annual flu shot.

  • Standard Dose Flu Shots - These flu vaccines are produced with viruses grown inside the eggs. Standard dose flu vaccines come in a variety of brands. These vaccinations are safe to administer to infants as young as six months. Most flu shots are injected with a needle into the arm's muscle. For individuals six months of age and older, Afluria Quadrivalent can be administered either by needle or by jet injector (for people 18 through 64 years only).

  • Cell-Based Flu Vaccine - Instead of hen's eggs, the flu viruses used in cell-based vaccines are cultured in cells of mammalian origin. Compared to conventional, egg-based flu vaccines, they provide greater protection. Flucelvax quadrivalent is recommended for individuals aged six months and older and contains a virus grown in cell culture. This vaccine contains no eggs at all.

  • Recombinant Flu Vaccine - The vaccine is made using recombinant technology. In the manufacturing process, neither chicken eggs nor the flu virus is used. In order to stimulate a stronger immune response, it contains three times as much antigen (vaccine component that helps in developing immunity against flu virus) as other standard-dose inactivated flu vaccines. Recombinant technology was used to create the Flublok quadrivalent vaccine, which is permitted for use in adults and children over the age of 18.

  • High-Dose Flu Vaccine - The vaccine has a stronger immune response as it contains four times the antigen of other standard-dose inactivated flu vaccines. Eggs are used for the culture of viruses. Fluzone high-dose quadrivalent is a medication that can be used by patients 65 and older.

  • Adjuvanted Flu Vaccine - An adjuvant (MF59) is used to make this vaccine (an ingredient that helps create a stronger immune response). Adults over 65 years are permitted to use the Fluad quadrivalent vaccine. It is manufactured using the egg-based process.

  • Live-Attenuated Flu Nasal Spray Vaccine - It is produced using the egg-based method. It is approved for use in people ages two to 49 and is made with attenuated (weakened) live flu viruses. It is not advised to administer this vaccine to those who are pregnant, immunocompromised, or have certain medical conditions. FluMist quadrivalent is a nasal spray that protects against all four subtypes of influenza viruses.

What Is the Effectiveness of the Seasonal Influenza Vaccination?

The effectiveness of the influenza vaccine can vary. The level of protection offered by a flu shot varies from season to season and is partially influenced by the age and general health of the recipient as well as the similarity, or match, between the viruses in the vaccine and those spreading within the community. It is possible to quantify the significant benefits of flu vaccination in terms of preventing flu illness and complications in years when the vaccine match is good. The benefits of the influenza vaccine are listed below:

  • Flu vaccination prevents sickness from the flu.

  • The flu vaccination lessens the severity of illness in those who receive it but still become ill.

  • Influenza vaccines decreases the risk of hospitalization due to the flu.

  • Pregnant women who receive an influenza vaccination are protected from the virus both during and after delivery. The infant also gets protected for the initial few months.

What Are the Adverse Effects of Influenza Vaccination?

  • The most frequent side effects seen after influenza vaccination are tenderness and inflammation at the site of the injection.

  • Muscle pain, headache, rise in body temperature, weakness, and nausea are the other symptoms.

  • The vaccination can also cause dizziness.

  • Severe allergic reactions are uncommon; however, they can typically happen between a few minutes and a few hours after getting the shot. People who are allergic to an ingredient in the vaccine, such as egg protein or other ingredients, may experience allergic reactions. A few of the symptoms of severe allergic reactions are breathing issues, hoarseness or wheezing, hives, paleness, weakness, a fast heartbeat, or dizziness.

Why Does a Person Get Infected Despite Influenza Vaccine Administration?

There are several reasons why an individual could experience flu symptoms even after receiving a flu shot.

  • Other respiratory viruses can infect people and cause illness during flu season. They can also cause symptoms comparable to the flu. Flu shots protect against influenza and its complications and not other infections.

  • Before or after the two-week window that the body needs to build immune defense after vaccination, people can be exposed to influenza viruses. A person may contract flu as a result of this exposure after getting vaccinated.


Influenza infections are very common and can be seen in people of all age groups. Vaccination is safe and reliable against influenza infection. Since the immunity obtained after vaccination decreases over time, it is advised to get vaccinated annually. The most widely used influenza vaccines around the world are inactivated influenza vaccines. People still fall sick after vaccination; however, the severity and impact of the infections are very low.

Frequently Asked Questions


During Which Season Is the Influenza Vaccine Required?

In the majority of people, one dose of flu vaccine is sufficient to offer the needed protection. The vaccination is usually preferred in the months of September and October. Ideally, it is advisable that everyone gets vaccinated by the end of October. By this, the body will have enough time to produce antibodies against the flu.


Why Is the Vaccine for Flu Seasonal?

The main purpose of flu vaccines is to protect one against infection and illness caused by the flu viruses, which are most prevalent in the flu season. Since the outer structures of these viruses keep changing constantly, a new vaccine is required every year. Recently, inner structures in the influenza protein coat that are similar in all strains of flu viruses have been found.


What Are the Recommended Guidelines for Seasonal Influenza Vaccine?

Routine annual influenza vaccination is suggested for those aged six months or older who do not have any other contraindications. The vaccine used should be recommended, age-appropriate, and licensed. Such vaccines are recommended even for pregnant ladies. Kids younger than nine years of age who receive a flu shot for the first time should receive two doses.


How Many Doses of Flu Vaccine Should One Take in a Year?

The influenza vaccine is given annually. Kids aged six months to eight years who have received less than two influenza vaccine doses or whose history of influenza vaccination is not known should receive two doses with a gap of at least four weeks. Flu vaccination is necessary for those who are at an elevated risk of developing flu-related complications.


Is a Flu Vaccine Required Every Year in India?

Getting a flu shot is not mandatory in India. However, it is recommended for vulnerable populations. Getting a flu vaccination will minimize the impact by either preventing one from acquiring the infection or, even if one gets the infection, it will be minor. Different influenza vaccines have been approved for different age groups.


How Long Do the Effects of the Flu Vaccine Last?

The flu shots offer protection from the influenza virus for about six months. It is recommended that adults get their yearly flu shots in September or October. Children under eight years of age require two doses of the vaccine and it is recommended to get their first shot in July or August.


Is Seasonal Flu a Normal Infection?

Seasonal flu is very common, and the number of people infected by influenza every year can only be approximately estimated since not everyone seeks medical care or gets tested. A majority of people recover from symptoms like fever within a week without any medical attention. However, the high-risk groups may be seriously affected.


Who Requires an Influenza Vaccine?

Children younger than five years of age, especially those younger than two years, are at an elevated risk of developing serious flu-related complications. Also, pregnant women and those with certain chronic (long-term) health issues should get a flu vaccination. The vaccine used should be recommended, age-appropriate, and licensed.


Is the Influenza and Flu Vaccine the Same?

The influenza infection is shortly called the flu and is caused by a virus. Hence, influenza and flu vaccines are the same. The main purpose of flu vaccines is to protect one against infection and illness caused by the flu viruses, which are most prevalent in the flu season. The influenza vaccine should be ideally taken annually.


What Are the Advantages of an Influenza Vaccination?

The advantages are as follows:

- Shortens the length of stay at the hospital due to flu.

- Minimizes the risk of death from flu.

- Minimizes the risk of admission to the intensive care unit (ICU) due to flu.

- Acts as a preventive tool for those with chronic health issues.

- Can be lifesaving in children and beneficial in pregnant women.


Is the Flu Vaccine Effective?

The flu vaccine is about 40 to 60 percent effective. High-dose flu vaccines are approved for use in the elderly aged 65 years and above. The Fluzone high-dose quadrivalent vaccine contains four times the antigen than the standard flu vaccines. It is a four-component flu vaccine.

Source Article IclonSourcesSource Article Arrow
Dr. Basti Bharatesh Devendra
Dr. Basti Bharatesh Devendra



influenza vaccine
Community Banner Mobile
By subscribing, I agree to iCliniq's Terms & Privacy Policy.

Source Article ArrowMost popular articles

Ask your health query to a doctor online

Community Medicine

*guaranteed answer within 4 hours

Disclaimer: No content published on this website is intended to be a substitute for professional medical diagnosis, advice or treatment by a trained physician. Seek advice from your physician or other qualified healthcare providers with questions you may have regarding your symptoms and medical condition for a complete medical diagnosis. Do not delay or disregard seeking professional medical advice because of something you have read on this website. Read our Editorial Process to know how we create content for health articles and queries.

This website uses cookies to ensure you get the best experience on our website. iCliniq privacy policy