Vaccines Health Center

Influenza Vaccine (Flu Shot and Nasal Spray) for Adults

The influenza vaccine is a yearly vaccine that protects you from getting the flu, a viral respiratory illness that spreads very easily. The flu can lead to serious health complications and possibly death.

The best way to prevent the flu is to get vaccinated. There are two types of flu vaccines:

• Flu shot: The flu shot is typically given to adults in a muscle in the upper arm. It is an inactive vaccine, which means it is made using dead bacteria. The dead germs cannot make you sick.
• Nasal spray: The nasal spray flu vaccine is a live attenuated influence vaccine, or LAIV. Unlike the flu shot, it is made from live, but weakened, influenza viruses. However, you cannot get the flu from the nasal spray vaccine. Only certain adults under age 50 may receive the nasal spray.

The three or four flu strains covered by the flu vaccine differ from year to year. That’s because the flu viruses are constantly changing. Scientists develop a new flu vaccine each season based on research that predicts which strains will be most likely to make you sick. For example, the 2012-2013 flu shots for adults were designed to protect against three influenza virus strains: the 2009 H1N1, H3N2-like virus, and an influenza B virus.

When Should Adults Be Vaccinated?

Flu seasons also vary, depending on where you live. Flu season can run from October to May. You should get vaccinated as soon as the vaccine becomes available. It takes about two weeks for the flu vaccine to start working, so you want to make sure you are fully protected as soon as possible. Generally, the seasonal flu vaccine is available from September until spring. 

Which Adults Should Get a Flu Vaccine?

The CDC recommends that adults receive a flu vaccine every year, especially those who are at high risk for developing flu-related complications and those who care for or live with such people, such as health care workers.

You are more likely to develop serious flu-related complications and should get a flu vaccine if you have:

• Asthma (even if it's mild or controlled) or other lung disease
• Brain, spinal cord, or nerve disorders or injury such as stroke, epilepsy, mental retardation, muscular dystrophy, cerebral palsy, or spinal cord injury
• Diabetes and other endocrine disorders
• Epilepsy
• Kidney disease or damage
• Heart disease
• Liver disease or damage
• Metabolic disorders (such as inherited metabolic disorders and mitochondrial disorders)
• Morbidly obese (BMI of 40 or greater)
• Sickle cell disease and other blood disorders
• A weakened immune system due to certain diseases or medical treatments

Your risk of developing flu-related complications is also increased if you are:

• Older than 50
• Pregnant
• American Indian or Alaskan Native

You should also get a flu vaccine if you live in a nursing home or other long-term care facility.