influenza vaccine
Quick Summary
The influenza vaccine, commonly known as the flu shot, is a medical intervention designed to protect against influenza viruses. Influenza itself is an acute viral infection affecting the respiratory tract, characterized by fever, chills, weakness, and body aches.123
Vaccines work by introducing a weakened or inactive form of a pathogen, or its components, to the body. This prompts the immune system to produce antibodies, creating immunity without causing illness. The flu vaccine's effectiveness varies annually, typically ranging from 40% to 60%. This variability is due to the rapid evolution of influenza viruses through a process called antigenic drift. Public health organizations like the World Health Organization analyze circulating strains to guide vaccine production, but new variants can emerge.413
Annual vaccination is recommended because immunity wanes and viruses change. The vaccine is most effective when administered in the fall. It not only protects individuals but also contributes to herd immunity, reducing virus spread within communities and indirectly protecting vulnerable populations.1
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