Since the screening policy prevented CBZ-SJS/TEN in HLA-B*15∶02 carriers in the post-policy period and six individuals were needed to be screened to detect one genetic carrier, as the quotient of the number needed to screen to detect one biomarker carrier divided by the CBZ-SJS/TEN risk among HLA-B*15∶02 carriers, 442 individuals would need to be screened to prevent one case of CBZ-induced SJS/TEN (see Formula 5 in Appendix S1). Here, HLA-B is linked to toxic epidermal necrolysis.