Quantifying fomite hotspots and targeted hygiene impacts in a hotel lobby.

Environmental surfaces in public settings serve as reservoirs for microbial pathogens, including norovirus, rhinovirus, and adenovirus, which can persist and spread through hand-to-fomite contact. Despite limited evidence of SARS-CoV-2 fomite transmission, hygiene protocols were widely intensified during the pandemic. This study evaluates viral spread and infection risks in a hotel lobby and assesses the efficacy of a Targeted Hygiene intervention designed to reduce contamination while minimizing excessive chemical use. A viral tracer study, using bacteriophage Phi X174, and human behavior observations were utilized to monitor surface contamination patterns, followed by Quantitative Microbial Risk Assessment (QMRA) to estimate infection probabilities. Tracer organisms seeded on high-touch surfaces spread to 50 % of sampled fomites within 4 h. A subsequent Targeted Hygiene intervention, using disinfecting wipes, sprays, or aerosols tailored to surface types, resulted in a statistically significant 97.36 % reduction in viral concentrations (1.57 log reduction, p < 0.0001). The proportion of cross-contaminated surfaces (i.e., non-seeded sites testing positive) decreased from 13 % to 2 %, and the overall percentage of positive surfaces dropped from 50 % to 42 %. QMRA modeling demonstrated that infection risks from a single fomite-hand-face contact were highest for rhinovirus, rotavirus, and adenovirus. Following intervention, infection risk was reduced by over 97 % for all modeled pathogens. Risk levels for all viruses and bacteria met the U.S. EPA and WHO benchmark of less than 1 infection per 10,000 exposures used in drinking water guidelines. Notably, bacterial infection risks, already low pre-intervention, were further reduced to meet the more stringent 1 infection per 1,000,000 risk threshold. This is the first study to integrate real-world human behavior, viral tracer data, and QMRA modeling to assess Targeted Hygiene in a hospitality setting. Findings support the implementation of evidence-based hygiene protocols that prioritize high-risk surfaces and timing, offering a sustainable approach to reducing infection risks in public environments.