Univariable and multivariable analysis of the factors associated with antibody titer ≥1∶40 to pandemic (H1N1) 2009 by viral neutralization among 101 healthcare workers who reported receipt of pandemic (H1N1) 2009 vaccine.

a<p>Multiple imputation was used to adjust for a small amount of missing data on some characteristics.</p>b<p>Model 1: adjusted for the variables of age group and vaccination history in 2008–09.</p>c<p>Model 2: adjusted for the variables of age group and vaccination history in 2007–08.</p>d<p>Model 3: adjusted for the variables that had p-value<0.2 in univariable analyses, i.e. age group, vaccination history in 2007–08, and vaccination history in 2008–09.</p>