Breakout Group: Best Methods for Studying Contact Transmission November 4, 2010 and November 5, 2010 – Atlanta, GA “Understanding the Modes of Influenza Transmission” Workshop

What are the key questions/ gaps remaining in understanding the contribution of contact transmission to the spread of influenza among humans?

Contact Transmission Breakout Group: Remaining Key Questions/ Gaps  Methodological issues  PCR identification and quantification VERSUS culture viability VERSUS human infectivity  Lack of evidence for contribution of contact transmission on human influenza:  Infectious dose Effect of underlying immunity  Survival on various surfaces, especially hands  Role of eyes, lips, nose, mouth exposure  Environmental microbiology of influenza  Level of contamination of various surfaces Significance of heavily contaminated environments  Contribution of humidity, temperature, uv, matrix, to survival

What are the best study designs and their pro’s/ con’s? What study designs would be best for understanding the contribution of contact transmission to the other transmission routes?

Contact Transmission Breakout Group: Best Study Design and pro’s/ con’s  Survival of virus on surfaces, especially hands as a function of temperature, humidity, matrix, uv.  Pros: Basic environmental microbiology needed to inform human studies  Cons: Does not prove role in contact transmission in humans  Human inoculation experiments, focusing on roles of lips, eyes, nose, mouth as entry portals  Pros: Address major gaps  Cons: Not demonstrate role in natural infection. Ethical concerns. Confounded by differences in strain, concentration, matrix. Expensive.  Suggestion: Do first in ferrets, especially eye inoculation.

Contact Transmission Breakout Group: Best Study Design and pro’s/ con’s  Determine environmental burden of influenza – laboratory & field studies  Pros: Inform human studies and models  Cons: Does not prove contact transmission  Human challenge studies:  Pros: Can selectively block different modes of transmission; human infections, can study interventions; able to control for confounders better than field studies  Cons: Expensive, ethical issues, limited virus strains, not natural infections  Suggestion: Use naturally infected donors, but logistically very problematic

Contact Transmission Breakout Group: Best Study Design and pro’s/ con’s  Hand washing studies:  Pros: Best way of investigating value of intervention  Cons: Does not effectively address role of contact transmission. Lots of confounders. Lots of conflicting results. Lack of positive result does not discard contact transmission.