Influenza vaccine

Purpose:

The influenza vaccine, commonly known as the flu shot, is designed to protect individuals from contracting influenza viruses, which can cause seasonal flu outbreaks.

Composition:

Influenza vaccines contain inactivated or weakened forms of the influenza virus strains expected to circulate during the upcoming flu season. The composition of the vaccine may vary each year to match the prevalent strains.

Mechanism of Action (MOA):

Upon administration, the influenza vaccine stimulates the immune system to produce antibodies against the influenza virus strains present in the vaccine. These antibodies provide protection by recognizing and neutralizing the virus if the individual is exposed to it in the future.

Types of Influenza Vaccines:

  1. Trivalent Inactivated Vaccines (TIV): Contains three strains of inactivated influenza virus.
  2. Quadrivalent Inactivated Vaccines (QIV): Contains four strains of inactivated influenza virus.
  3. Live Attenuated Influenza Vaccines (LAIV): Contains weakened live influenza virus strains.

Administration:

The influenza vaccine is typically administered via injection into the muscle (intramuscular) or just under the skin (subcutaneous). LAIV is administered as a nasal spray.

Indications:

  • Annual vaccination is recommended for individuals aged six months and older to prevent seasonal influenza infections.
  • Especially recommended for individuals at high risk of complications from influenza, including young children, older adults, pregnant women, and individuals with certain medical conditions.

Contraindications:

  • Severe allergic reactions to components of the vaccine, including eggs or previous doses of the vaccine.
  • Individuals with a history of Guillain-Barré syndrome within six weeks of receiving a previous influenza vaccine.

Side Effects:

Common side effects of the influenza vaccine include:

  • Soreness, redness, or swelling at the injection site.
  • Low-grade fever.
  • Muscle aches.
  • Fatigue.

Storage and Handling:

Influenza vaccines should be stored according to the manufacturer’s instructions, usually in a refrigerator at temperatures between 2°C and 8°C. Proper storage and handling are essential to maintain the vaccine’s potency and effectiveness.

Disposal:

Unused or expired influenza vaccines should be disposed of according to local regulations for medical waste disposal.

Precautions:

  • Individuals with a history of severe allergic reactions should be monitored closely after vaccination.
  • Vaccination may be delayed for individuals with acute febrile illness.

Monitoring and Adverse Events Reporting:

Healthcare providers should monitor individuals for immediate adverse reactions following vaccination. Adverse events should be reported to the Vaccine Adverse Event Reporting System (VAERS) for surveillance and monitoring.

Importance of Vaccination:

Influenza vaccination is a crucial public health measure to reduce the burden of seasonal influenza, prevent illness and complications, and protect vulnerable populations from severe outcomes.