**3. Predicted virucidal efficacy data for microbicides, including surface and hand hygiene agents, against the WHO Priority List viruses**

The hierarchy of pathogen susceptibility to microbicides [5–10] (**Figure 1**) suggests that certain classes of microbicidal agents should display virucidal efficacy against lipid-enveloped viruses in general. For example, lipid-disrupting agents, such as alcohols, quaternary ammonium compounds (e.g., benzalkonium chloride), phenolics (e.g., para-chloro-meta-xylenol or PCMX), detergents (e.g., soap and Triton X-100), and organic acids (e.g., citric, lactic, and salicylic acids) would be expected to display similar virucidal efficacy for the WHO Priority List viruses, which are exclusively lipid-enveloped viruses. The same is true for proteindenaturing agents (alcohols, phenolics, oxidizers, and organic acids), and genomedegrading agents, such as alcohols and oxidizing agents. Of course, microbicides with virucidal efficacy against less susceptible pathogens, including mycobacteria, large and small non-enveloped viruses, and bacterial spores/protozoan oocysts, and prions, would certainly be expected to display virucidal efficacy against each of these WHO Priority List viruses. Having made these predictions, what do the empirical testing data tell us?
