'Wild to Mild': How Flu Shots Work

Many people who skip their annual flu shot use the same refrain: “The flu shot doesn’t work.” It’s true that many people still contract the virus even after being vaccinated—but that doesn’t mean the shot is ineffective.

Scientists have long recognized that the flu vaccine is best at reducing the severity of infections, not necessarily preventing the flu altogether. In a recent interview with Scientific American, William Schaffner, MD, an infectious disease specialist at Vanderbilt University Medical Center, provided more detail on how the flu shot works.

He explained that vaccine-induced defenses offer deeper protection within the body, often protecting the heart, liver and kidney from a severe to life-threatening influenza infection. However, those same vaccine-induced defenses aren’t as effective in the respiratory tract where mild influenza occurs. That’s why people who are vaccinated could still experience mild cases of the flu with less severe respiratory symptoms such as a runny nose.

This year, the Centers for Disease Control and Prevention (CDC) changed their public education strategy for the flu shot, launching a new campaign that focuses on the key benefits of getting vaccinated. Called “Wild to Mild,” the campaign illustrates how the vaccine reduces the strength of a flu infection and shortens the length of illness.

The CDC expects multiple viruses to spread this fall and winter, including flu, COVID-19 and respiratory syncytial virus (RSV). Respiratory diseases can be very serious, especially among people at higher risk of developing serious complications, and CDC urges everyone to get up to date on their recommended vaccines.

“The flu vaccine is developed each year based on the flu viruses that are circulating at the end of the last year’s flu season,” Dr. Schaffner adds. “That’s why everyone 6 months and older should have a flu vaccine each year before the start of flu season.”

For those younger than 65, the CDC does not recommend any one flu vaccine more than another. However, those 65 and older should get a higher-dose flu shot, such as a quadrivalent vaccine, for better protection.

“In these older populations, they work about 20% better than the standard vaccine,” Schaffner says.

For help getting a flu vaccine near you, Vanderbilt Health offer dozens of locations with convenient hours throughout Middle Tennessee—and can even bring a provider to you. Check out this site for five types of convenient care.