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.

aMultiple imputation was used to adjust for a small amount of missing data on some characteristics.bModel 1: adjusted for the variables of age group and vaccination history in 2008–09.cModel 2: adjusted for the variables of age group and vaccination history in 2007–08.dModel 3: adjusted for the variables that had p-value