Going for three: what is the role for triplex testing for HSV-1, HSV-2, and VZV?

Herpes simplex virus-1 (HSV-1), HSV-2, and varicella zoster virus (VZV) are common causes of mucocutaneous lesions. Diagnostic methods have shifted from culture or direct fluorescent antibody testing to nucleic acid amplification tests (NAATs), but testing is (i) not often undertaken or (ii) often specific for either HSV-1/2 or VZV based upon classic clinical findings associated with typical disease. A recent study by B. W. Buchan and P. Pancholi published in ASM Case Reports (2:e00112-25, 2025, https://doi.org/10.1128/asmcr.00112-25) highlights the limitations of this approach, revealing a substantial number of cases where provider-ordered testing missed the causative virus. Accurate viral identification is critical in these cases, as missed or misdiagnosis impacts patient management. Treatment regimens, including antiviral dosage and duration, vary among clinical presentations of HSV-1, HSV-2, and VZV. More importantly, infection control protocols differ among these pathogens. Many cases of VZV require airborne and contact isolation in healthcare settings to prevent nosocomial transmission, a precaution not necessary for most HSV-1/2 infections. In some cases, clinical diagnosis may be insufficient for differentiation among HSV-1, HSV-2, and VZV. More studies are needed to help identify use cases where triplex testing is most appropriate, but broader availability and implementation of triplex NAATs have the potential to promote better patient management and infection prevention practices.