Healthy, fit, rarely get sick? You still need a flu shot!

flu shot photoPhoto © AdobeStock

Know your options, and get vaccinated every year

Hospitalization and death from the flu seems like something that only happens to those who are well into retirement age, or to babies and young children. Adults who are relatively fit and active, who eat a healthy diet, and who don’t have chronic illnesses often decide that there is no need to get vaccinated.

Hard data from the Centers for Disease Control and Prevention (CDC), however, tell a different story. It is true that most hospitalizations and deaths happen among the very young and very old. But, life-threatening flu can hit even relatively young, healthy adults!

In the 2015-2016 flu season, nearly 10 million adults between the ages of 18 and 49 were diagnosed with the flu. Of those, about 3.5 million adults were sick enough to go to their doctor, meaning time off work and other life activities. About 54,000 adults aged 18 to 49 were hospitalized because their flu was so severe, and about 1,500 died. The numbers are much higher for people aged 50 to 64, with about 75,000 hospitalizations and 2,500 deaths in 2015-2016.


The CDC recommends that everyone aged 6 months and older should get the flu vaccine each year. This includes pregnant women. The best time to get it is in September and October, but it is still better to get it later in the flu season than to not get it at all.

Know your options

There are several different kinds of flu vaccine available. Some are trivalent, meaning they protect against three strains of virus:

  1. Type A, subtype H1N1
  2. Type A, subtype H3N2
  3. Type B, Victoria lineage

Other flu vaccines are quadrivalent, meaning they protect against the same three types of virus as trivalent vaccines, plus they protect against a second Type B virus (Yamagata lineage).

Options for the trivalent flu vaccine are listed in the table below:

Type Delivery Method Age Group Notes
Standard-dose, inactivated Injection in arm with needle 4 years and older
  • Contains inactivated (dead) virus.
  • The virus is grown in eggs, killed, and purified.
Standard-dose, inactivated Jet injector (high-pressure, narrow stream of fluid that penetrates the skin) 18-64 years old
  • Contains inactivated (dead) virus.
  • The virus is grown in eggs, killed, and purified.
Standard-dose, recombinant Injection in arm with needle 18 years and older
  • Contains proteins from flu virus, but does not contain the inactivated (dead) virus.
  • Flu virus proteins are grown in the lab in cell cultures, then purified.
  • 100% egg-free.
Standard-dose, inactivated, with adjuvant Injection in arm with needle 65 years and older
  • Contains inactivated (dead) virus.
  • The virus is grown in eggs, killed, and purified.
  • A naturally occurring substance that increases the immune response to the vaccine is added. This substance (squalene) is called an adjuvant.
  • Offers better protection for older people than standard-dose, inactivated vaccine.
High-dose, inactivated Injection in arm with needle 65 years and older
  • Contains inactivated (dead) virus at high dose.
  • The virus is grown in eggs, killed, and purified.
  • High-dose, inactivated vaccine offers better protection for older people than standard-dose, inactivated vaccine.

Options for the quadrivalent flu vaccine are listed in the table below:

Type Delivery Method Age Group Notes
Standard-dose, inactivated Injection in arm with needle 6 months and older (various versions available for different age groups)
  • Contains inactivated (dead) virus.
  • The virus is grown in eggs, killed, and purified.
Standard-dose, inactivated, intradermal Intradermal (injected into the skin instead of the muscle; uses a much smaller needle than the regular flu shot) 18-64 years old
  • Contains inactivated (dead) virus.
  • The virus is grown in eggs, killed, and purified.
Standard-dose, recombinant Injection in arm with needle 18 years and older
  • Contains proteins from flu virus, but does not contain the inactivated (dead) virus.
  • Flu virus proteins are grown in the lab in cell cultures, then purified.
  • 100% egg-free.
Standard-dose, inactivated, cell culture Injection in arm with needle 4 years and older
  • Contains inactivated (dead) virus.
  • The virus is grown in animal cells in a test tube, then the virus is killed, and purified.
  • 100% egg-free.

Is one vaccine better than another?

There are many different options for flu vaccines. There are vaccines for older people, vaccines for babies and toddlers, vaccines for children and adolescents, and vaccines for adults aged 18-64. Within any age group, the CDC does not recommend one type over another type.

The most important thing is to get vaccinated, whichever option you choose. All of the options provide protection against seasonal influenza infection.

Further reading

The Centers for Disease Control and Prevention. About Flu.

The Centers for Disease Control and Prevention. Seasonal Flu Shot.

The Centers for Disease Control and Prevention. Misconceptions About Seasonal Flu and Flu Vaccines.

About the Author

Jillian Lokere

Jillian is a science/medical writer who specializes in communicating complex scientific and medical ideas in a meaningful and engaging way. She holds a master’s degree in biomedical science from Harvard University and a bachelor’s degree in biological science from Stanford University. In addition, Jillian conducted two years of doctoral-level research in the Department of Genetics as part of Harvard’s Biological and Biomedical Sciences program. She has more than 13 years of experience in writing about the life sciences and medicine.