There was no difference in abstinence rates between NicVAX and placebo from weeks 9 to 52 [ 27.7 versus 30.0 % , odds ratio ( OR ) = 0.89 , 95 % confidence interval ( CI ) = 0.62-1 .29 ] or weeks 37 to 52 ( 33.8 versus 33.2 % , OR = 1.03 , 95 % CI = 0.73-1 .46 ) .