Infectious Diseases in Obstetrics and Gynecology The populations considered in the overall analysis included the Intent-to-Treat (ITT) exposed, consisting of all subjects who received at least one dose of investigational product. This was the primary population for assessing safety. Also considered was the Intent-to-Treat Crossover (ITTC) population consisting of all ITT subjects who had at least one PCR result in each treatment period. This was the primary population for assessing eﬃcacy. The First Period Eﬃcacy population consisted of all patients with eﬃcacy data in the ITT-Exposed, with the exception of 2 subjects whose data was compromised (see Section 3). This was the primary population for assessing eﬃcacy in the ﬁrst treatment period. The treatment comparison for continuous endpoints, including the primary endpoint, was tested using nonpara- metric crossover analysis methods in the ITTC population [21]. The test of treatment diﬀerence was preceded by a test of carryover eﬀect using a Wilcoxon rank-sum test at the 5% level of signiﬁcance [21]. If this test was signiﬁcant, then the treatment comparison would be tested using The First Period Eﬃcacy population only. This analysis was carried out as a supporting analysis in any case because the test of carryover may have relatively low power. The binomial secondary endpoints were analyzed using Prescott’s method [22]. Time to ﬁrst genital recurrence was evaluated with Kaplan-Meier estimates and log-rank test using the First Period Eﬃcacy population and data in treatment period 1. The reported safety measures were adverse events and laboratory data. 3. Results 3.1. Subject Characteristics. Seventy subjects from 14 centers in the United States were randomized into the study, 35 subjects to the VAL-PBO treatment sequence, and 35 subjects to the PBO-VAL treatment sequence. During the course of routine monitoring, errors in sample identiﬁcation were discovered for two subjects at one site. The error was felt to compromise the integrity of the data; therefore, swab samples from two subjects in the VAL-PBO sequence group were excluded from the eﬃcacy analysis. An additional three subjects were “lost to follow-up” early in treatment period 1. These three subjects had some swabbing samples but all PCR assay results were missing, leaving 65 subjects in the First Period Eﬃcacy population. Twenty of the 70 (29%) subjects in the ITT population prematurely withdrew from the study (11 while receiving valacyclovir, 9 while receiving placebo). The primary reason for withdrawal was “lost to followup” (n = 8, 11%), followed by “other reason” (n = 6, 9%), “subject decided to withdraw” (n = 4, 6%), and adverse event (n = 2, 3%). At least one major protocol deviation was recorded for 35 (50%) subjects randomized. Deviations included failure to take at least 80% of double-blind study medication (n = 13, 37%) and genital/anal-rectal swab PCR results on fewer than 85% of study days (n = 20, 57%). The study population was predominantly female (70%); 51% were white (Table 1). Of the 70 subjects randomized, 9 (13%) were HSV-2 seronegative at entry indicating newly Table 1: Demographics ITT Population. 3 Demographics No. of subjects Female gender, n (%) Mean Age, years (SD), range White, n (%) Black, n (%) HSV-1a and HSV-2 Antibody Positive, n (%) HSV-1 Antibody Positive, HSV-2 Antibody Negative, n (%) HSV-1 Antibody Negative, HSV-2 Antibody Positive, n (%) HSV-1 and HSV-2 Antibody Negative, n (%) VAL-Placebo Placebo-VAL 29 (9), 18–49 33 (10), 20–58 35 22 (63) 19 (54) 13 (37) 17 (49) 2 (6) 13 (37) 3 (9) 35 27 (77) 17 (49) 15 (43) 19 (54) 1 (3) 12 (34) 3 (9) a One patient in each treatment group had an HSV-1 equivocal result and are included here. acquired HSV-2 infection. Note that one of these 9 subjects did not have eﬃcacy data in treatment period 1. Of the 8 in the First Period Eﬃcacy population, 6 were also HSV- 1 negative, indicating primary infection. All nine subjects presented with laboratory conﬁrmation of HSV-2 infection by culture or PCR at screen or upon initial diagnosis made within 4 months of randomization. These subjects represent a subset of the population who had a clearly documented recent HSV-2 infection. 3.2. Viral Shedding. The primary eﬃcacy endpoint was the diﬀerence in mean percent of all days with HSV-2 shedding as determined by a type-speciﬁc HSV PCR assay. For the ITTC population, shedding was reported on a mean 13.5% of all days in subjects while receiving placebo compared to a mean 2.9% of days in subjects while receiving valacyclovir (P < .001), a signiﬁcant decrease representing a 78% reduction in total HSV-2 shedding (Table 2). The test of period diﬀerences as well as the test of residuals (carryover eﬀect) was not signiﬁcant, P = .362 and P = .401, respectively. The supporting analysis of total days with shedding during treatment period 1 was consistent with the twoperiod carryover analysis. In the ﬁrst treatment period, there was a statistically signiﬁcant (83%) reduction in total days with shedding (Table 2). The mean percent of all days with subclinical HSV-2 shedding was a secondary endpoint (Table 2). In the ITTC population, subclinical shedding was identiﬁed on a mean 11% of days in subjects while receiving placebo compared to a mean 2.4% of days in subjects while receiving valacyclovir (P < .001), a signiﬁcant decrease representing a 78% reduction in subclinical shedding. Signiﬁcant diﬀerences between valacyclovir and placebo also were demonstrated in the percent of days with clinical shedding, proportion of