Serum IgA titers against three different influenza stimuli (rHA, Vaxigrip and vaccine against influenza) after nasal vaccination. Median, range and response frequency in each group are shown. FalkebornTina BråveAndreas LarssonMarie ÅkerlindBritt SchröderUlf HinkulaJorma 2013 <p>Abbreviations: rHA =  recombinant hemagglutinin, NA  =  Not applicable.</p>