Dixie E. Snider, M.D., M.P.H. Senior Advisor, Office of the Director, CDC Update on Approaches to Understanding Human Influenza Transmission November 4, 2010 Background for this Meeting Office of the Director Office of the Associate Director for Science (OADS)

Outline of Presentation  Selected Chronology of Events since April, 2009  High Level Summary of the “State of the Science”  Why the mode or modes of transmission matter to public health  Conclusion

Chronology of Events  April, 2009 – Outbreaks of disease caused by a novel, influenza A (H1N1) strain are detected in Mexico and the United States.  May, 2009 – CDC issues interim recommendations for infection control in healthcare settings. Based primarily on concerns about the severity of disease caused by this new strain, N95 respirators were recommended rather than surgical masks (the standard for seasonal influenza protection).

Chronology of Events (Continued) June, 2009 – Acting CDC Director orders guidelines for influenza infection control in healthcare settings be reviewed and revised as necessary. External stakeholders are to be engaged. Early July, 2009 – Informal CDC working group is created to carry out the task. Members represent various CDC components with expertise in the area.

Chronology of Events (Continued)  July, 2009 – WG engages external stakeholders, including healthcare infection control experts, occupational health and safety experts, OSHA, and labor unions representing HCP.  July, CDC WG identifies differences of opinion about the use of surgical masks vs. N-95 respirators as a major obstacle to developing consensus guidelines  July, 2009 – IOM is asked by CDC and OSHA to convene a panel to specifically address the respiratory protection issue, without considering “economic and logistical” factors.

Chronology of Events (Continued)  September 1, 2009 – IOM panel meets  September 3, 2009 – IOM panel issues a letter report with two recommendations:  Recommendation 1: Use Fit-Tested N95 Respirators  Recommendation 2: Increase Research on Influenza Transmission and Personal Respiratory Protection “The need for research in a number of areas was striking. Due to the lack of a strong and conclusive evidence base, the committee concluded that determination of the relative contribution of each route of influenza transmission is essential for long-term preparedness planning.”

Chronology of Events (Continued) September 29, 2010 – CDC Director attends meeting at the White House and emerges with a charge to “fast track” research which would close critical knowledge gaps noted by the IOM. October, 2009 – Amidst great controversy, CDC issues new interim infection control guidance which continues to recommend N95 respirators, but attempts to address feasibility and logistical issues. October, 2009 – WHO identifies the mode or modes of influenza transmission as a major knowledge gap.

Chronology of Events (Continued)  October, 2009 – Ten CDC staff members are identified to serve on an “Influenza Research Agenda Steering Committee”. One objective is to create a “fast tack” agenda.  November 2010 – the committee completes its work, presents its proposal to leadership, and receives approval to proceed to implement five projects.

Summary of the “Fast Track” Agenda  Study to understand the modes of influenza transmission  Study of the persistence of viable influenza virus in aerosols  A direct comparison of N95 respirators vs. surgical masks for protection of healthcare personnel  Study of the dispersal of viable airborne influenza viruses and the effect of ultraviolet light  The effect of exclusion policies (e.g., school closures) on influenza transmission

High Level View of “The State of the Science”  The literature on influenza transmission is rather large but is not definitive and often contradictory  There is evidence both for and against each of three modes of transmission, i.e., direct or indirect contact, large droplets, and droplet nuclei (aerosol) transmission  Inappropriate inferences characterize some studies, e.g., close range spread does not necessarily prove large droplet transmission  Study designs often have serious limitations, but optimal designs have not been put forth

Why Does the Mode of Transmission of Influenza Matter to CDC? Guideline Development  Infection control in healthcare settings  Infection control in the workplace  Infection control in schools  Infection control in public transportation settings Purchases for the Strategic National Stockpile Assistance to our Federal, national, state, and local constituencies, e.g., OSHA, SHEA Meet Expectations of the Public Meet Expectations of Executive and Legislative Branches

Conclusions  Events over the past 18 months have brought attention to the fact that the mode or modes of transmission of influenza are not well understood  Filling this knowledge gap would serve a number of public health purposes  We need your individual advice on the optimal way or ways to fill this knowledge gap

Thank you for Coming! Questions ?