Question special
Lead Moderator

Hello! Welcome to the discussion of the recent NEJM article by Jackson et al. on influenza vaccine effectiveness in the US during the 2015/2016 season. I am privileged to be a moderator for this conversation and to have the opportunity to gain some additional insights from the authors and our expert panel.

In this study, Jackson and colleagues used a test-negative study design with surveillance data from the Influenza Vaccine Effectiveness Network and found that overall influenza vaccine effectiveness against acute respiratory illness due to any laboratory-confirmed influenza virus was 48% in the 2015/2016 season. Importantly, the quadrivalent live attenuated vaccine (LAIV4) was not effective, including against influenza A(H1N1)pdm09, despite the fact that the LAIV4 product contained a slightly different influenza A(H1N1) strain (A/Bolivia/559/2013) than the one used in prior LAIV products. These results echo the findings of multiple studies from previous seasons that have found that LAIV4 is inferior to inactivated influenza vaccine (IIV).

To kick off the discussion, given the data added by this study, what are some of the reasons that LAIV4 might be less effective than IIV?