Vaccines by disease: Learning more about the
inactivated influenza vaccine

This vaccine is important because it protects against the influenza virus. Each year, approximately 220,000 people in the United States are hospitalized because of influenza (“the flu”), and 36,000 die. There are two kinds of influenza vaccines: the inactivated (killed) influenza vaccine and the live attenuated (weakened) influenza vaccine. Anyone 6 months of age or older can receive the inactivated vaccine but the live attenuated vaccine is recommended only for healthy, non-pregnant people without asthma between the ages of 2 and 49 years.

Influenza can cause high fevers, pneumonia and seizures in children. Prevention is the key to not contracting the flu, and the most effective preventive method is receiving an annual influenza vaccination.

Who should receive the inactivated influenza vaccine?  People at increased risk of developing complications from influenza should receive the inactivated influenza vaccine every year including: All infants and children between the ages of 6 months through 18 years People over 50 years of age People living in long-term care facilities that house patients with chronic medical conditions People with long-term health problems including asthma, blood disorders, heart disease, kidney disease, lung disease and metabolic diseases such as diabetes People with weakened immune systems People with muscle or nerve disorders People who can easily transmit influenza viruses to those at high risk for complications (see above and also including infants less than 6 months of age), including health care professionals, childcare workers and children who live with high-risk persons All people who want to reduce the risk of getting influenza and passing it to other people People who live in college residences/dormitories and who will be traveling with tour groups should consider receiving the inactivated influenza vaccine. The inactivated influenza vaccine also can be given to anyone who wants to reduce their risk of contracting influenza. Inactivated Influenza vaccine should not be given to: People who are allergic to eggs People with severe allergies to any vaccine component People who are moderately or severely ill. They should wait until they have recovered to get this vaccine. It can take up to two weeks for inactivated influenza vaccine to become fully effective. The best time to get this vaccine is in October or November, but even a late vaccination in December and later may be beneficial. Flu season may start as early as October usually peaks in February and can extend through late May.

When did the inactivated influenza vaccine become available?
Since 1945, influenza vaccines have been available in the United States. The vaccine is modified each year with three virus strains that are predicted to be in the United States during the upcoming winter. The inactivated (killed) vaccine (TIV), commonly referred to as the flu shot, is given by injection. A second flu vaccine, the live attenuated influenza vaccine (LAIV) is given via nasal spray (a separate description of this vaccine is available for review).

How does someone become infected with influenza?
Influenza is most commonly spread from person to person. It also may be spread when a healthy person touches something with the flu virus on it (e.g., hands of an infected person, discarded tissue, etc) and then touches the nose or mouth.

How effective is the inactivated influenza vaccine?
When the virus strains in the vaccine match those viruses circulating in the U.S., the inactivated influenza vaccine can protect between 45 percent and 90 percent of vaccinated healthy children. Inactivated influenza vaccine also decreases middle ear infections in young children by approximately 30 percent.

The inactivated influenza vaccine may prevent up to 90 percent of influenza cases in vaccinated healthy adults under the age of 65.

Are there any serious side effects of the inactivated influenza vaccine?
Serious side effects from the inactivated influenza vaccine are quite rare. Mild side effects may include:

• injection-site soreness
• fever

It is a myth that inactivated influenza vaccine causes influenza. The inactivated vaccine contains killed viruses and cannot give you the flu. Also, it takes 2 weeks for the flu vaccine to protect so you can get influenza before that period has been completed.

How do I learn more about this vaccine?
The best person to ask about this or any vaccine is your child’s pediatrician or your primary health care provider. Your provider can answer your questions and give you more information on the inactivated influenza vaccine.

Immunization is the best thing you can do for your child and yourself to protect against influenza.