INTRODUCTION: An intradermal version of Fluzone® split-virion inactivated 
trivalent influenza vaccine, containing 9 µg hemagglutinin per strain of A/H1N1, 
A/H3N2, and one B lineage virus (Fluzone Intradermal, Sanofi Pasteur), became 
available in the US during the 2011-2012 influenza season for adults 18-64 years 
of age. In advance of the 2015-2016 season, Fluzone Intradermal was replaced 
with Fluzone Intradermal Quadrivalent vaccine, which contains 9 µg hemagglutinin 
per strain of the two A-strain viruses and both B-strain lineage viruses 
(Victoria and Yamagata).
AREAS COVERED: This literature review summarizes the history and mechanism of 
intradermal vaccination, discusses the clinical trial results supporting the 
immunogenicity and safety of Fluzone Intradermal Quadrivalent vaccine, and 
describes the unique microinjection system used to deliver Fluzone Intradermal 
Quadrivalent. Expert commentary: Fluzone Intradermal Quadrivalent may boost 
confidence in influenza vaccination with the addition of a second B-lineage 
strain. By using an innovative microinjection system, the vaccine is also 
designed to address some of the logistic challenges faced by healthcare 
providers administering immunizations.