The intervention increased uptake of the first ( first-time invitees : 28.4 % vs. 19.6 % , odds ratio [ OR ] = 1.63 , 95 % confidence interval [ CI ; 1.08 , 2.47 ] ; previous nonattenders : 23.6 % vs. 10.4 % , OR = 2.65 , 95 % CI [ 1.61 , 4.38 ] ) and third ( first-time invitees : 22.4 % vs. 12 % , OR = 2.15 , 95 % CI [ 1.32 , 3.50 ] ; previous nonattenders : 12.4 % vs. 3 % , OR = 4.28 , 95 % CI [ 1.92 , 9.55 ] ) vaccinations .