A flu shot injection is an annual immunization delivered via needle to stimulate antibody production against influenza viruses. The Centers for Disease Control and Prevention (CDC) recommends this vaccine for everyone aged six months and older.
The injection contains inactivated flu viruses or a single gene from a flu virus. When administered, it triggers the immune system to produce antibodies without causing illness. This process typically takes about two weeks to provide protection.
According to the CDC, flu vaccines reduce the risk of illness by 40% to 60% during seasons when most circulating flu viruses are well-matched to those in the vaccine.
Flu shots come in several formulations. The most common types include:
| Type | Description | Age Group |
|---|---|---|
| Standard dose | Contains inactivated flu viruses | 6 months and older |
| High-dose | Contains four times the antigen amount | 65 years and older |
| Recombinant | Made using viral genes, egg-free | 18 years and older |
| Nasal spray | Live, weakened virus (not an injection) | 2 years and older |
The CDC recommends annual flu vaccination for everyone aged six months and older, with few exceptions. High-risk groups include:
Many people believe the flu shot can give you the flu. However, the inactivated viruses in the shot cannot cause infection. Some may experience mild side effects like soreness at the injection site or low-grade fever, but these are not the actual flu.
Another myth is that the flu shot isn't necessary if you had the flu before. Immunity from natural infection doesn't last long, and the flu shot protects against multiple strains of the virus.
While the flu shot is effective, it's not perfect. Maintaining good hygiene practices, staying home when sick, and avoiding close contact with infected individuals can provide additional protection.