What to Do Now to Reduce Influenza’s Toll This Winter
Each year, influenza takes its toll—particularly among the elderly. In the United States, about 3000 people succumb to this viral infection in years with low influenza activity; during epidemics, up to 50,000 die.1
Fortunately, there is still time to protect patients this coming flu season. Systemic immunization remains the most effective means of minimizing the morbidity and mortality associated with influenza.
Here is an overview of this year’s influenza vaccine and the CDC’s recommendations for vaccination.2
THIS YEAR’S VACCINE
Because new variants of influenza type A generally appear every year and new strains of type B make their debut every few years, annual influenza immunization is mandatory. The strains selected for inclusion in the 2012–2013 influenza vaccines are:
•A/California/7/2009 (H1N1)-like virus.
•A/Victoria/361/2011 (H3N2)-like virus.
•B/Wisconsin/1/2010-like virus.
While the H1N1 virus is the same as what was included in the 2011–2012 influenza vaccines, this year’s influenza H3N2 and B viruses differ from those in the 2011–2012 influenza vaccines.
AVAILABLE VACCINE PRODUCTS
Several influenza vaccines will be available during the 2012–2013 season, and all of them contain the same antigenic composition. Consult the package inserts for more information about additional components of the various vaccine formulations, as well as indications, contraindications, and precautions.
Trivalent inactivated vaccine (TIV) preparations, with the exception of Fluzone Intradermal (Sanofi Pasteur), should be administered intramuscularly. For adults and older children, the deltoid is the preferred site. Infants and younger children should be vaccinated in the anterolateral thigh.
The TIV preparation Fluzone Intradermal is administered intradermally. This vaccine is indicated for persons aged 18 through 64 years and contains less antigen than intramuscular TIV preparations (9 µg rather than 15 µg of each strain per dose) in a smaller volume (0.1 mL rather than 0.5 mL). The vaccine is given via a single-dose, prefilled microinjection syringe. The preferred site of administration is over the deltoid muscle. This vaccine is an alternative to other TIV preparations for persons aged 18 through 64 years, with no preferential recommendation.
An alternative TIV for persons aged 65 years and older is Fluzone High-Dose (Sanofi Pasteur). This vaccine contains 60 µg of hemagglutinin per vaccine strain (rather than 15 µg per strain as in other intramuscular TIV preparations). No preference is indicated for this TIV versus other TIV preparations.
The intranasally administered live attenuated influenza vaccine (LAIV) FluMist (MedImmune) is indicated for healthy, nonpregnant persons aged 2 through 49 years. Within this patient group, no preference is indicated for LAIV versus TIV; however, persons with a history of egg allergy should receive TIV rather than LAIV.
The recently approved quadrivalent LAIV, FluMist Quadrivalent (MedImmune), is not expected to become available until the 2013–2014 influenza season. It will likely replace the currently available seasonal trivalent FluMist formulation.
WHO SHOULD RECEIVE THE VACCINE?
Routine vaccination is recommended for all persons aged 6 months and older (Table). Children aged 6 months through 8 years should be given 2 doses of influenza vaccine (administered a minimum of 4 weeks apart) during their first season of vaccination to optimize immune response.
A change from the 2011 CDC recommendations is that children aged 6 months through 8 years who have never received influenza vaccine or who have not received two or more doses of seasonal influenza vaccine since July 2010 should receive two doses of 2012–2013 vaccine (given at least 4 weeks apart). This is because of the antigenic novelty of the 2009 (H1N1) pandemic virus, which is anticipated to continue circulating during the 2012–2013 influenza season. Children who last received seasonal (trivalent) influenza vaccine before the 2010–2011 season but did not receive a vaccine containing 2009 (H1N1) antigen (either seasonal vaccine since July 2010 or monovalent 2009 [H1N1] vaccine) will not have received this antigen.
WHEN TO GIVE THE VACCINE
Start offering the influenza vaccine as soon as it becomes available to allow time for the production of protective antibody levels. Continue vaccination efforts throughout the duration of the influenza season. Vaccine administered in December or later, even if influenza activity has already begun, is likely to be beneficial during most influenza seasons. While influenza outbreaks can occur as early as October, disease activity typically peaks in January or later.
GUIDELINES FOR PATIENTS WITH EGG ALLERGY
The 2011 guidelines for influenza vaccination in persons with egg allergy were more permissive than in previous seasons.3 The CDC recommends that persons who have experienced only hives from consuming eggs can receive TIV intramuscularly as long as they are treated by a health care provider who is familiar with the potential manifestations of egg allergies and can be observed by a health care professional for at least 30 minutes after receiving each dose. LAIV should not be used in these patients.
Some persons who report allergy to egg might not actually be allergic to eggs. Those who are able to eat lightly cooked egg (eg, scrambled eggs) without reaction are unlikely to be allergic. However, egg-allergic persons might tolerate egg in baked products (eg, bread or cake); thus, tolerance to egg-containing foods does not exclude the possibility of egg allergy. Such allergy can be confirmed by a consistent medical history of adverse reactions to eggs and egg-containing foods, in addition to skin and/or blood testing for immunoglobulin E antibodies to egg proteins.
Persons who have had reactions to egg involving angioedema, respiratory distress, lightheadedness, or recurrent emesis, or persons who required epinephrine or other emergency medical intervention (particularly reactions that occurred immediately or within minutes to hours after egg exposure) are more likely to have a serious systemic or anaphylactic reaction on re-exposure to egg proteins. Before vaccination, such persons require further risk assessment by a physician who has expertise in the management of allergic conditions.
In general, the CDC recommends that all vaccines be administered in settings in which personnel and equipment for rapid recognition and treatment of anaphylaxis are available. A previous severe allergic reaction to influenza vaccine, regardless of the component suspected to be responsible for the reaction, is a contraindication to vaccination.
1. Thompson MG, Shay DK, Zhou H, et al. Estimates of deaths associated with seasonal influenza—United States, 1976-2007. MMWR. 2010;
59(33):1057-1062.
2. Grohskopf L, Uyeki T, Bresee J, et al. Prevention and control of influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP)—United States, 2012–13 influenza season. MMWR. 2012;61(32);613-618.
3. Grohskopf L, Uyeki T, Bresee J, et al. Prevention and control of influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP), 2011. MMWR. 2011;60(33):1128-1132.