The present invention provides a semi-quantitative lateral flow assay device and method for generating semi-quantitative data from a lateral flow assay. The device comprises a thin, porous hydrophilic substrate wherein the substrate includes a star-shaped or other geometry taken in plan view having a liquid sample-receiving central region and multiple arms that extend or radiate out from the central region. Each arm includes a reaction zone formed by the presence of an analyte-capturing agent wherein the reaction zone of each arm is located at a different distance from the central region such that the analyte in the sample is captured accumulates in different quantities at at least some of the reaction zones of the arms in a manner that can be analyzed to yield semi-quantitative data from lateral flow assays. The reaction zones on the arms can be analyzed visually and/or by software analysis of a digital image based on color saturation, grayscale, or other characteristics of the reactions zones due to the presence of different amounts of analyte to produce semi-quantitative data of the total loading of a virus or other agent of interest of a patient's blood.