Influenza, commonly known as the flu, is a viral infection that targets the respiratory system—i.e. the nose, throat and lungs. Symptoms can include cough, congestion, muscle aches, fever and chills. When left untreated, the flu can lead to long-term hospitalization and even death.
The Centers for Disease Control and Prevention recommends everyone get a flu vaccination. Certain groups, namely children, seniors and people with an immunodeficiency, are more vulnerable to infection than others. For optimal protection, individuals should be vaccinated before peak flu season, which can occur between December and February.
Like the virus itself, the flu vaccine is constantly changing. Researchers create formulas based on the previous year’s strain to combat the latest iteration. Each vaccine contains a small amount of the virus, which triggers the body’s natural defenses. This exposure helps the immune system better identify and combat incoming pathogens.
Despite its viral origin, the flu vaccine does not spread the infection. It’s manufactured from an inactive strain, meaning it’s no longer a biological threat. In some instances, people experience side effects like low-grade fever, headache or muscle aches after taking the shot. Others may develop redness, soreness or swelling at the site of injection. These issues are usually resolved in one or two days.
There are multiple flu vaccines available. In the United States, trivalent and quadrivalent are the most common. The trivalent vaccine protects against three viral strains, while the quadrivalent inhibits four. Standard versions are grown and synthesized from chicken eggs. Yet, there are alternatives for individuals with egg-sensitivities such as a recombinant quadrivalent (for people age 18 and up) and a cell culture-based vaccine (for people age four and up).
Generally, flu vaccines can be administered to individuals six months and older. But people allergic to gelatin and certain antibiotics as well as those with Guillain-Barré Syndrome should talk to their doctor before receiving the shot. It’s possible for the vaccine to cause short-term and long-term health issues.
Although the success rate varies from year-to-year, the flu vaccine has been shown to reduce the chance of infection by 40% to 60%. Those who do contract the virus experience much milder symptoms and have fewer influenza-related complications.
This year, public health officials are saying it’s more important than ever to get the flu shot to lessen the strain on hospital systems burdened by COVID-19 patients.