Statistical analysis
REGRESSION, ADVERSE EVENT
The sample size of 29 per group would give 90% power to determine the significant difference in ISR between the two intervention groups, with a two-tailed test, 0.75 effect size, 0.05 significance level, and 1/1 allocation ratio, using Gpower software version 3.1.9.7.In a randomized clinical trial, the intention to treat (ITT) is the primary analysis. Given that the study population included all randomly assigned patients who received the allocated booster dose, ITT and per protocol (PP) analyses will invariably produce identical results. Descriptive analysis was reported as mean with standard deviation (SD), median with interquartile range (IQR) for quantitative variables, and frequency with percent for qualitative variables. The variability of ISR was reported using a 95% Confidence interval (CI) around the point estimate.The Chi-squared test was used to compare the distribution of a categorical variable. Adverse events were compared between groups using the Fisher exact test.The linear regression approach was used to investigate the predictors of serologic response following the booster dose. In univariate analysis, predictors associated with higher ISR value (p ≤ 0.2) are incorporated into a multivariable model. All the tests were considered two-way, and a p-value < 0.05 was reported as statistically significant. All statistical analyses were conducted using STATA version 17 (StataCorp, LP, College Station, TX, USA). GraphPad Prism software, version 9.5.1 (GraphPad Software Inc., San Diego, CA, USA), was used for the graphical presentation.