Influenza, commonly known as the flu, is a respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. Annual vaccination is recommended for most individuals six months of age and older to protect against this contagious disease. The vaccine helps the body develop antibodies to fight off influenza viruses, typically within two weeks. This preventive measure reduces the risk of severe illness, hospitalizations, and complications associated with influenza each year.
Common Terminology
In everyday conversations, the preventive measure against influenza is frequently called a “flu shot.” This term generally refers to the vaccine administered as an injection, typically into the arm muscle. “Influenza vaccine” is another widely used, more formal descriptor. These terms are often used interchangeably for the annual immunization against seasonal influenza viruses.
Official Medical Designations
Beyond common names, flu vaccines are categorized by formal medical designations based on their production methods and components. Inactivated influenza vaccines (IIVs) are a prevalent type, created from killed flu viruses. Live attenuated influenza vaccines (LAIVs) contain weakened, live flu viruses modified to prevent them from causing illness. Recombinant influenza vaccines (RIVs) are produced using genetic engineering techniques without using eggs.
Variations and Specific Formulations
The flu vaccine comes in several specific formulations, each designed to address particular needs or demographics. Standard-dose inactivated flu shots are widely available and approved for most age groups, typically providing protection against four influenza virus strains. High-dose flu vaccines, such as Fluzone High-Dose, contain four times the antigen of standard vaccines, recommended for individuals 65 years and older. Adjuvanted flu vaccines, like Fluad, include an adjuvant that enhances the immune response, suitable for older adults with a diminished immune response.
Cell-based flu vaccines, such as Flucelvax, are manufactured using cultured mammalian cells instead of chicken eggs. Most flu vaccines are egg-based, grown in fertilized chicken eggs. The live attenuated influenza vaccine (LAIV) is administered as a nasal spray, offering an alternative for healthy individuals aged 2 through 49 years who prefer avoiding an injection. These diverse formulations allow healthcare providers to select the most appropriate vaccine for each individual based on their age, health status, and other considerations.
Brand Names
Flu vaccines are also recognized by various proprietary brand names under which they are marketed by pharmaceutical companies. Common examples include Fluzone, which offers standard-dose and high-dose options, and FluLaval. Afluria is another brand available in different formulations, including quadrivalent versions. For the nasal spray vaccine, FluMist is a well-known brand. These brand names typically correspond to one of the official medical designations or specific formulations, such as inactivated, recombinant, or live attenuated vaccines.