Everything Your Family Needs to Know About the Flu Shot

There are many different types of flu shots — some in higher doses than others — but a few of the most common include:

• Trivalent flu shot, designed to protect against three different flu strains (two influenza A strains, one influenza B strain) using a killed version of the virus.
• Quadrivalent flu shot, designed to protect against four different flu strains (two influenza A strains and two influenza B strains) using a killed version of the virus.
• Quadrivalent nasal spray vaccine, designed to protect against four flu strains (two influenza A strains and two influenza B strains) using a live virus.