Isaac Perales, PharmD Intern & Jennifer Seltzer, PharmD
September 20, 2016
During the summer of 2016, there has been controversy over FluMist® vaccine effectiveness, a live attenuated influenza vaccine (LAIV) that utilizes a nasal spray delivery system. In June 2016, the Advisory Committee on Immunization Practices (ACIP) advised against FluMist® use for the upcoming 2016-2017 influenza season.1 In September 2016, the American Academy of Pediatrics (AAP) also recommended against FluMist® use in their 2016-2017 influenza prevention and control guidelines.2 These recommendations originate from the Centers for Disease Control and Prevention (CDC) and are reflected in the Morbidity and Mortality Weekly Report (MMWR) from August 26th.3
During the 2015-2016 influenza season, the CDC reported > 26,000 laboratory confirmed cases of influenza infection.4 Influenza is a respiratory infectious disease caused by influenza viruses. Transmission occurs mainly via person-to-person inhalation of respiratory droplets but can also occur through contact with surfaces contaminated with infectious respiratory secretions. Adults are considered infectious from 1 day before until 7 days after the onset of illness and children could potentially be infectious for > 10 days. The pathogenesis of influenza is not well understood in humans but the severity of infection is associated with the balance between viral replication and the host immune response. In most adults, the illness is mild and symptoms typically resolve within 3 to 7 days. However, the highest rates of severe illness, hospitalization, and death occur among those > 65 years of age, < 2 years of age, and individuals with underlying medical conditions. Severe illness is likely caused by an inability of the host defense mechanisms to inhibit viral replication and an overproduction of cytokines leading to tissue damage. Classic influenza signs and symptoms include fever, headache, myalgia, malaise, nonproductive cough, sore throat, and rhinitis. The most effective strategy to control influenza infection is through vaccination preventive measures.5
FluMist® was originally FDA approved in 2003 as active immunization to prevent influenza caused by influenza A and B subtypes in individuals 2-49 years of age. While the exact mechanism of protection against influenza is not fully understood, serum antibodies, mucosal antibodies, and influenza-specific T cells may play a role. The most common adverse effects of this vaccine included fever, sore throat, and runny nose or nasal congestion.6 This product remains the only live attenuated influenza vaccination available and the only influenza vaccination delivered as an intranasal spray.7
In June 2016, ACIP reviewed data evaluating quadrivalent LAIV (LAIV4) and inactivated influenza vaccine (IIV) effectiveness during the 2015-2016 influenza season. During this season, the A(H1N1)pdm09 influenza strain was predominant. Data analysis from the U.S. Influenza Vaccine Effectiveness Network showed no significant vaccine effectiveness among children 2-17 years of age with LAIV4 for all influenza A and B viruses combined (vaccine effectiveness, 3%; 95% CI, -49-37) or for influenza A(H1N1)pdm09 alone (vaccine effectiveness, -21%; 95% CI, -108-30).3 Additionally, AAP calculated that children who received LAIV4 were 2.5 times more likely to develop influenza from any virus type and 3.67 times more likely to develop influenza from the A(H1N1)pdm09 influenza strain compared to children who received IIV.2
In light of the evidence presented, ACIP and AAP recommend against LAIV4/FluMist® use in any setting for the 2016-2017 influenza season. More information regarding current 2016-2017 influenza vaccination recommendations can be found on the CDC website (http://www.cdc.gov/flu/).
- Centers for Disease Control and Prevention. ACIP votes down use of LAIV for 2016-2017 flu season. Available at: http://www.cdc.gov/media/releases/2016/s0622-laiv-flu.html. Accessed September 12, 2016.
- AAP committee on infectious diseases. Recommendations for prevention and control of influenza in children, 2016–2017. Pediatrics. 2016;138(4):e20162527
- Grohskopf LA, Sokolow LZ, Broder KR, et al. Prevention and control of seasonal influenza with vaccines. MMWR Recomm Rep. 2016;65(No. RR-5):1–54. doi: http://dx.doi.org/10.15585/mmwr.rr6505a1
- Davlin SL, Blanton L, Kniss K, et al. Influenza activity – United States, 2015-16 season and composition of the 2016-17 influenza vaccine. MMWR Morb Mortal Wkly Rep. 2016;65:567–75. doi: http://dx.doi.org/10.15585/mmwr.mm6522a3.
- Njoku JC, Hermsen ED. Chapter 87. Influenza. In: DiPiro JT, Talbert RL, Yee GC, et al. eds. Pharmacotherapy: a pathophysiologic approach, 9e. New York, NY: McGraw-Hill; 2014. http://accesspharmacy.mhmedical.com.ezproxy.lib.utexas.edu/content.aspx?bookid=689&Sectionid=45310533. Accessed September 12, 2016.
- Influenza vaccine live, intranasal (FluMist® Quadrivalent) package insert. MedImmune, LLC., July 2016.
- Influenza Types A and B Vaccine. Facts & Comparisons® eAnswers [database online]. Hudson, OH: Wolters Kluwer Clinical Drug Information, Inc.; 2016. Available at: http://online.factsandcomparisons.com.ezproxy.lib.utexas.edu/index.aspx. Accessed September 12, 2016.