Overview

Given the speed with which viruses transmitted by the respiratory route spread globally (e.g. SARS, the 2009 influenza pandemic, MERS), epidemics caused by these viruses pose the greatest threats to global public health. Surprisingly, little is known about the mechanisms by which these viruses are transmitted; much of what is believed to be known being based on dogma than “fact”. Such knowledge gaps include the relative importance of contact, fomites, and air-borne (large droplet vs. small droplet) spread; the aero-biology of virus transmission; what interventions prevent such transmission; the role of viral “quasi-species” in transmission; and viral / host determinants of adaptation of animal viruses for transmission in humans. In turn, these knowledge-gaps compromise the impact and rational use of non-pharmaceutical interventions for infection prevention and control.

Ongoing work addressing some of these gaps in knowledge tends to occur within individual silos, by pathogen (e.g. influenza, RSV, rhinovirus, measles, MERS) or by experimental approach (e.g. those working with experimental animal models; basic virology; epidemiology; aero-biology; infection control). This conference aims to cut across these divisions to bring together researchers working with different viruses and using different experimental approaches. We expect these interactions to deepen understanding and to foster collaborations internationally.

Themes

Theme 1: Respiratory virus transmission among humans

There are still many uncertainties about the dynamics of respiratory virus transmission from human to human. Major questions that will be discussed at the conference include: What proportion of respiratory virus transmission occurs through the aerosol (fine particle) route? How many virions are involved in transmission from person to person, for different viruses? How do host, viral and environmental factors influence the routes of transmission? How much viral evolution occurs at the transmission event, versus during the course of infection within a host? Which locations or environments are more supportive to viral transmission? How do all of these issues vary between viruses?

Theme 2: Animal models for virus transmission

Transmission is the consequence of complex virus-host interactions. Experimental animal models provide data on viral and host factors associated with enhanced transmission potential and on mechanisms (e.g. aerobiology; modes of transmission) of transmission. Animal models provide the benefit of being able to control for variations often observed in human transmission studies due to differences in prior immunity, genetic factors, age etc, and when combined with serial sampling with pathology, immuno-histochemistry, or labelled viruses, permit insights not achievable solely with epidemiological or human volunteer challenge studies. By bringing together researchers working on experimental animal models, human epidemiological or experimental challenge studies (Theme 1) we will facilitate better understanding of respiratory virus transmission.

Theme 3: Determinants of transmission

Zoonotic transmission can lead to emergence of explosive epidemics or pandemics, SARS, the 2009 pandemic, MERS being recent examples. However, the understanding of the viral and host determinants of the emergence of viruses efficiently transmissible in humans remains poorly understood. Such understanding is important for surveillance at the animal-human interface and to risk-assess the many zoonotic transmission events that regularly occur and prioritise those for which medical countermeasure development needs to be prioritized.

Theme 4: Control of respiratory virus transmission

A wide variety of non-pharmaceutical measures are used to control respiratory virus transmission. Major questions that will be discussed at the conference include: Which measures are more effective in reducing the transmission of respiratory viruses, such as source control measures, environmental controls, etc? What is the risk of transmission in different settings and the impact of control measures on risk? What are the best approaches to control nosocomial transmission of respiratory viruses? What is the potential for new strategies to control respiratory virus transmission? How do all of these issues vary between viruses? What are the options for prevention of zoonotic emergence?