Median CD4 count at HIV diagnosis was similar for cases and controls (535 [IQR 384–666] vs. 523 [IQR 377–690] cells/μL; p = 0.940), but lower for cases at zoster diagnosis (436 [IQR 277–631] vs. 527 [IQR 367–744] cells/μL; p = 0.007). This evidence concerns the gene CD4 and herpes zoster.