Understanding the Influenza Vaccine

What is the Influenza Vaccine?

The influenza vaccine is an intramuscular injection designed to protect against three or more strains of influenza viruses.

Types of Influenza Vaccines

It is essential to recognize that the influenza vaccine is highly dynamic, changing annually due to new antigenic variations caused by antigenic drift. Consequently, last year’s vaccine may not provide protection against this year’s viruses. There are currently two main types of influenza vaccines available:

1. Inactivated Influenza Vaccine

The inactivated influenza vaccine is developed by cultivating the influenza virus in embryonated chicken eggs. The virus is then chemically inactivated through the disruption of its envelope using detergents, followed by the partial purification of Hemagglutinin and Neuraminidase proteins. This vaccine is administered via intramuscular injection, typically in the deltoid muscle, and may also be given as an intradermal injection. It poses a low risk of complications and is safe for individuals with egg allergies when observed in a healthcare setting.

Can You Get Infected from the Inactivated Influenza Vaccine?

No, the inactivated virus cannot replicate or reproduce, which means there is no risk of infection from this vaccine.

Who Should Receive the Inactivated Influenza Vaccine?

The inactivated influenza vaccine is recommended for individuals with weakened immune systems, including:
– Children over 6 months
– HIV-positive patients
– Organ transplant recipients (immunosuppressed individuals)
– Pregnant women
– Diabetic patients
– Asthma sufferers
– Individuals with kidney problems
– Those who are in close contact with immunosuppressed individuals

2. Live Attenuated Influenza Vaccine

The live attenuated influenza vaccine is created through a genetic assortment that produces weakened strains of the virus with seasonal Hemagglutinin and Neuraminidase genes. This vaccine is administered as a nasal spray. The term “attenuated” refers to the alteration of the virus, which remains alive but weakened, allowing the immune system to respond effectively without causing severe illness.

Can You Get Sick from the Live Attenuated Influenza Vaccine?

In most cases, individuals will not develop a full-blown influenza illness from this weakened virus, as the immune system is typically capable of defending against it. However, there is a slight risk associated with this vaccination.

Who Should Receive the Live Attenuated Influenza Vaccine?

Experts recommend this vaccine for healthy individuals aged 2 to 49, provided it is administered in a healthcare setting.

Antibody Response to the Vaccine

The primary targets for antibodies generated by the vaccine are Hemagglutinin and Neuraminidase proteins. Hemagglutinin antibodies are crucial for preventing the virus from entering cells, as they bind to sialic acid. The serum antibody responses to the influenza vaccine can be measured using the Serum Hemagglutinin Inhibition (HAI) assay.

Types of Influenza Vaccines by Composition

Trivalent Influenza Vaccine

The trivalent influenza vaccine contains Hemagglutinin and Neuraminidase components from two subtypes of influenza A (H1N1 and H3N2) and one strain of influenza B.

Quadrivalent Influenza Vaccine

The quadrivalent influenza vaccine is designed to protect against four strains: two influenza A and two influenza B viruses.

Side Effects of the Influenza Vaccine

Like all vaccines, the influenza vaccine may cause some side effects. The live attenuated influenza vaccine may lead to temporary reactions, including:
– High fever
– Weakness
– Allergic reactions
– Difficulty breathing
– Hoarseness or wheezing
– Swelling around the eyes or lips
– Hives
– Paleness
– Weakness
– Fast heartbeat or dizziness

Understanding these aspects of the influenza vaccine can help individuals make informed decisions about their health and vaccination options.