Rx Update: October 2003

Influenza Virus Vaccination

Joan Murhammer, R.Ph., Mary Ross, R.Ph., M.B.A., Kevin Bebout, R.Ph.
Peer Review Status: Internally Reviewed

Influenza outbreaks typically occur during the winter months and can cause disease among all age groups. Influenza activity usually occurs between November and April. Rates of infection are highest among children, but rates of serious illness and death are highest among persons greater than 65 years of age and persons of any age who have medical conditions that place them at increased risk for complications from influenza (see table below). Influenza illness is characterized by the abrupt onset of fever, myalgia, headache, severe malaise, nonproductive cough, sore throat, and rhinitis. Influenza is spread from person to person primarily through coughing and sneezing. Influenza virus vaccine is the primary method for protecting high-risk patients against the complications associated with influenza disease.

 

Patients at Increased Risk for Complications Due to Influenza Who Should Be Vaccinated

Everyone 65 years of age or older Residents of nursing homes and other chronic-care facilities that house persons who have chronic medical conditions Adults and children with chronic heart or lung problems, including asthma Persons who during the past year have regularly seen a doctor or have been admitted to a hospital for treatment of kidney disease, cystic fibrosis, chronic metabolic diseases such as diabetes, anemia, severe asthma, cancer, HIV, or other immunological disorders (or use certain types of medicines) that lower the body's normal resistance to infections Children and teenagers (6 months to 18 years of age) who are receiving long-term aspirin therapy and, therefore, may be at risk of developing Reye syndrome after influenza Women who will be in the second or third trimester of pregnancy during influenza season

Additional Persons Who Are Recommended for Influenza Vaccination

Persons aged 50 to 64 years - because of an increased prevalence of high-risk medical conditions Persons who can transmit influenza to those at high risk, including: Health-care workers Employees of nursing homes, chronic care facilities, and assisted living residences Persons who provide home care to persons in high-risk groups Household contacts (including children) of persons in high-risk groups Children 6 to 23 months old Household contacts of children < 6 months old

Inactivated influenza vaccines should not be administered if a patient has an anaphylactic hypersensitivity to eggs, has had a previous serious allergic reaction or other serious problems after getting an influenza vaccination, or currently has an acute or severe febrile illness. The most commonly reported local reaction to the inactivated influenza vaccine is soreness at the injection site, which generally lasts less than 48 hours. Systemic reactions (e.g., fever, malaise, myalgia, headache) can also occur.

The recommended doses of the inactivated influenza vaccine are listed in the table below. Two doses should be administered at least one month apart for children less than 9 years of age who are receiving influenza vaccine for the first time. One dose is adequate in subsequent years. The preferred site for infants and young children is the anterolateral aspect of the thigh using a 7/8 to 1 inch needle. For adults and older children, the recommended site for vaccination is the deltoid muscle using a >1 inch needle. It takes approximately two weeks for the vaccine to be effective against influenza. Annual vaccination with the current vaccine is necessary because immunity declines during the year after vaccination and viral strains in the vaccine vary from year to year.

Inactivated Influenza Vaccine Dosage Recommendations
Age Group	Dose	Number of Doses	Route
6 to 35 months#	0.25 ml	1 or 2*	IM
3 to 8 years	0.5 ml	1 or 2*	IM
> 9 years	0.5 ml	1	IM
# A preservative-free 0.25 ml syringe (Fluzone®) is available for children 6 to 35 months of age. * 2 doses one month apart if patient (< 9 years) is receiving vaccine for the first time.

Because the intranasal influenza virus vaccine (FluMist^®) is a live-virus vaccine and has the potential for viral shedding, inactivated influenza virus vaccine is the recommended vaccine for health-care workers and for family members and other close contacts of immunocompromised patients.

Title Page