*2.4. Statistical Analysis*

Descriptive statistics were used for the characterization of the patients studied. We compared the placebo and VLP 15 μg dose. The statistical analysis was performed using StataCorp software (2011 Stata Statistical Software—Release 12, College Station, TX: StataCorp LP). Descriptive statistics were used to characterize the categorical variables, expressed as a percentage. A bivariate analysis was performed for comparison among groups, using Fisher's exact test or chi-square test; *p* < 0.05 was considered statistically significant.

### **3. Results**
