Establishing the Dynamics of Environmental Influenza Virus Loads During Human Infection in a Tightly Controlled Indoor Setting

KARIN BRETT, Sterling Knight, Zachariah Broemmel, Byron Hauser, Elizabeth Petzold, Christopher Woods, Nicole C. Rockey, Duke University

     Abstract Number: 390
     Working Group: Bioaerosols

Abstract
Seasonal influenza viruses cause significant human health and economic burdens, resulting in over 200,000 hospitalizations and an estimated $11.2 billion in costs annually in the United States alone. These viruses spread through the environment when infected individuals emit virus-laden droplets and aerosols that deposit on surfaces or remain airborne before ultimately reaching a susceptible host and initiating an infection. Understanding how environmental loads vary by host, setting, and time into an infection is critical to accurately determining exposure risks associated with influenza virus spread in indoor environments. Defining the impact of environmental parameters (e.g., relative humidity, temperature, air exchange rate) on virus contamination is also beneficial for identifying effective engineering control strategies. While previous studies have successfully detected influenza virus nucleic acid and infectious virus loads in aerosols and on surfaces in real-world settings, these data are difficult to interpret because the sources and age of the detected viral loads are largely unknown.

Here, we address these knowledge gaps by using a controlled human infection model to assess environmental influenza virus contamination over the course of a viral infection, from pre-symptomatic to post-symptomatic illness. In this model, participants are inoculated with a seasonal influenza A virus strain and closely monitored over the subsequent eight-day quarantine period, allowing for the daily collection of aerosol and surface samples their rooms. Environmental samples are being assessed for viral RNA concentrations, and positive samples will be further evaluated for infectious virus loads. By working in this tightly controlled yet realistic setting, our results will establish how environmental loads vary by host, viral, and environmental factors. Ultimately, this research will inform more environmental monitoring work that can accurately assess exposure risks and identify when mitigation strategies should be employed to reduce influenza virus transmission in indoor settings.