On Wednesday June 22, 2016 the Center for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices (ACIP) voted against the use of the live attenuated influenza vaccine (LAIV), or “nasal spray,” for the 2016-2017 flu season.
Each flu season, the CDC conducts vaccine effectiveness studies and makes recommendations based on the results of these studies. The ACIP recommendation signifies how new data can ensure public health. This recommendation is built on data collected between 2013 and 2016, which showed “poor or relatively lower effectiveness of LAIV…” Thus, the ACIP has recommended that individuals who are 6 months of age or older be vaccinated with the inactivated influenza vaccine (IIV) or the recombinant influenza vaccine (RIV), which are administered as annual vaccinations.
The US Influenza Vaccine Effectiveness Network released data on the effectiveness of LAIV in children between 2 and 17 years of age during the 2015-2016 flu season, in late May. This data revealed that for study participants in that age group, LAIV showed 3% vaccine effectiveness (VE), meaning that participants received immeasurable protective benefits from this vaccine. On the other hand, participants between the ages of 2 and 17 years of age who received the IIV showed 63% VE. Further studies, not conducted by the CDC, supported the conclusion that LAIV was less effective than IIV.
This is not the first time that the CDC has made this recommendation. Previous CDC studies
, conducted on the 2013-2014 flu season, showed similar outcomes: LAIV should not be administered to healthy children between the ages of 2 and 8 years of age. However, during the 2014-2015 flu season, the recommended vaccines had no preference: either the LAIV or the IIV could be used.
The CDC recommendation states that the effectiveness of the flu vaccine changes from season to season based on several factors. These include the characteristics of the individual receiving the vaccine, the similarity between the virus used within the vaccine and the circulating influenza strain, as well as which vaccine is being used. As noted by the CDC, vaccines that use live viruses may cause a stronger immune response than those using inactivated viruses. With this in mind, it is no surprise that LAIV VE data collected prior to and right after the vaccine was licensed in 2003 as a one-injection trivalent vaccine, revealed that it was “either comparable to, or better than, IIV.” It is still unknown what has warranted LAIV’s recent poor performance.
LAIV is produced by MedImmune and sold under the name FluMist Quadrivalent. The company projected that 14 million vaccines would be sold in the 2016-2017 flu season. ACIP’s vote against the use of LAIV may affect vaccine providers and pediatricians alike, specifically since recent data suggests that one third of all flu vaccines administered to children are in fact nasal vaccines.
Final annual flu vaccine recommendations will be available in the CDC Morbidity and Mortality Weekly Report
either in the late summer, or early fall. The CDC still recommends that all people 6 months and older receive a flu vaccine.
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