A non-invasive blister fluid-based rapid test for point-of-care detection of varicella and herpes zoster: preliminary validation in a clinical setting

Abstract

Varicella and herpes zoster, caused by varicella-zoster virus (VZV), remain prevalent worldwide and can cause severe complications if diagnosis is delayed. Early detection within the 72-hour therapeutic window is essential for initiating antiviral therapy to reduce transmission, postherpetic neuralgia, and other complications. Few non-invasive point-of-care tests for VZV are currently available. In this preliminary clinical validation of 30 cases, we developed and evaluated a blister fluid-based lateral flow immunoassay for rapid VZV detection. The assay was tested using VZV standard solutions and blister fluid from patients and healthy controls. In real-world testing, direct visual interpretation achieved 80% sensitivity and 100% specificity within 15 minutes. Reflectance spectral analysis enabled quantitative measurement, with a limit of detection of 1.48 pg mL⁻¹ and a limit of quantitation of 42.9 pg mL⁻¹; smartphone-assisted analysis produced comparable results without laboratory equipment. Its rapid turnaround, non-invasive sampling, and portability make this approach suitable for diverse healthcare settings, including community-based and at-home use. This “blister fluid biopsy” strategy may facilitate timely intervention, improve patient outcomes, and strengthen infection control, particularly in resource-limited environments.