Seasonal Influenza Vaccination - Types and Benefits

Introduction:

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.

Conclusion:

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.