The Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices (ACIP) has voted that live attenuated influenza vaccine (LAIV), also known as the “nasal spray” flu vaccine, should not be used during the 2016–2017 flu season. The ACIP continues to recommend annual flu vaccination with either the inactivated influenza vaccine (IIV) or the recombinant influenza vaccine (RIV) for everyone 6 months of age and older.
The ACIP is a panel of immunization experts that advises the CDC. The committee’s vote was based on data showing poor or relatively lower effectiveness of LAIV from 2013 through 2016.
LAIV is sold in the United States as FluMist Quadrivalent (MedImmune) and was initially licensed in 2003 as a trivalent (three-component) vaccine. LAIV is currently the only non–injection-based flu vaccine available on the U.S. market.
In late May, preliminary data on the effectiveness of LAIV among children aged 2 years through 17 years during the 2015–2016 season became available from the U.S. Influenza Vaccine Effectiveness Network. Those data showed that the estimated LAIV vaccine effectiveness (VE) among study participants in that age group against any flu virus was only 3%. This estimate meant that no protective benefit could be measured. In comparison, IIV (flu shots) had a VE estimate of 63% against any flu virus among children aged 2 years through 17 years. Other (non-CDC) studies supported the conclusion that LAIV worked less well than IIV. The data from 2015–2016 followed two previous seasons (2013–2014 and 2014–2015) that showed poor and/or lower-than-expected VE for LAIV.
LAIV contains live, weakened influenza viruses. Vaccines containing live viruses can cause a stronger immune response than vaccines with inactivated virus. LAIV VE data before and soon after licensure suggested that it was either comparable with or better than IIV. The reason for the recent poor performance of LAIV is not known.
Vaccine manufacturers had projected that as many as 171 million to 176 million doses of flu vaccine, in all forms, would be available for the United States during the 2016–2017 season. The makers of LAIV had projected a supply of as many as 14 million doses of LAIV/nasal spray flu vaccine, or about 8% of the total projected supply. The ACIP’s vote could have implications for vaccine providers who have already placed vaccine orders. The ACIP recommendation may particularly affect pediatricians and other vaccine providers for children because data from recent flu seasons suggest that nasal spray flu vaccine accounts for approximately one-third of all flu vaccines given to children. The CDC says it will be working with manufacturers throughout the summer to ensure that there is enough vaccine supply to meet the demand.
The ACIP’s recommendation must be reviewed and approved by the CDC’s director before it becomes CDC policy. The final annual recommendations on the prevention and control of influenza with vaccines will be published in an issue of Morbidity and Mortality Weekly Report in late summer or early fall.
The CDC has recommended an annual influenza vaccination for everyone aged 6 months and older since February 24, 2010. The CDC and the ACIP briefly had a preferential recommendation for nasal spray vaccine for young children (during the 2014–2015 flu season); however, during the 2015–2016 season, influenza vaccination was recommended without any preference for one vaccine type or formulation over another.
Source: CDC; June 22, 2016.