showed a trendP<0.0001
On the other hand, the group of subjects who received PI vaccination showed a trend toward an increase in the median IgG titer (median values of 0.3 to 579 (P<0.0001), 0.00–401.4 (P = 0.3125), and 971.3 to 2163 (P = 0.3008) in group 1,2, and 3 respectively), except slight decrease of IgG value for Group 4 (median value of 1067 to 1021; P = 0.9717).