Organizers: Doris Bucher (New York Medical College) and Jennifer Henry (The New York Academy of Sciences)Presented by the Emerging Infectious Diseases & Microbiology Discussion Group and the Dr. Paul Janssen Memorial Series

Overview

Influenza viruses such as H1N1 continue to pose a major global public health problem, so understanding their pathogenicity and transmission is crucial. A symposium held on May 24, 2010, at the New York Academy of Sciences revisited the 2009 swine flu (H1N1) outbreak and examined strategies against future outbreaks. Invited speakers covered virulence, transmission, the New York City experience, vaccine development, and the public health implications of a worldwide pandemic. A roundtable discussion featuring all speakers then reflected on the successes and problems during the 2009 outbreak, debated whether this is now considered a rehearsal for more virulent outbreaks, and presented updated strategies to confront future pandemics.

In his examination of H1N1 virulence, Terrence Tumpey from the Centers for Disease Control and Prevention (CDC) discussed the use of a ferret model to investigate the pathogenesis and transmissibility of three 2009 H1N1 viruses compared with a seasonal H1N1 virus. Selected 2009 H1N1 isolates were assessed for their ability to cause disease, and were found to cause increased morbidity and exhibit less efficient respiratory droplet transmission in ferrets compared to the high-transmissible phenotype of a seasonal H1N1 virus. Anice Lowen of the Mt. Sinai School of Medicine reflected on transmission of the 2009 H1N1 pandemic influenza virus during the 2009 pandemic. Researchers studying the virus suggested that the 2009 pandemic strain spread with comparable or greater efficiency among humans than seasonal influenza viruses. It appeared that the unique constellation of gene segments comprising the 2009 H1N1 viral genome and/or adaptive changes that differentiate those gene segments from their swine precursors facilitated efficient human-to-human spread. Host and environmental factors also played a role in spread of the disease. The emergence of the swine-origin strain during the spring in the northern hemisphere was also important in shaping its epidemiology, as transmission continued throughout summer but peak influenza activity occurred later, during autumn and winter. Work in guinea pig models has found that aerosol transmission is dependent on humidity and temperature, suggesting that novel H1N1 epidemics will continue to adopt winter seasonality.

In a fascinating examination of pathology findings of all fatal 2009 influenza A/H1N1 viral infections seen in New York City, James Gill from the Office of Chief Medical Examiner summarized a review of all medical records, autopsy reports, microbiologic studies, and microscopic slides of the 34 people who died between May 15 and July 9, 2009. The majority of the 34 decedents (62%) were between 25 and 49 years of age, and most cases showed tracheitis, bronchiolitis, and diffuse alveolar damage. Bacterial pneumonia was detected in 55% of decedents, and underlying medical conditions (including cardiorespiratory diseases, immunosuppression, and obesity, as defined by a BMI >30) were associated with most deaths.

To address the role and response of the CDC, as the U.S. government primary front-line responder to all infectious disease outbreaks, Michael Shaw discussed their various pandemic response exercises, conducted in preparation for the appearance of new influenza pandemic strains. These preparedness assumptions were tested during the 2009 outbreak and required real-time reassessment and modification of response strategies. On reflection, systems put in place prior to the pandemic proved to be invaluable. Data and viruses were shared rapidly and openly, new diagnostic assays were deployed in record time, and a new vaccine (which proved to be an excellent match) was developed, tested, and dispensed with the cooperation of numerous government and private agencies and institutes. Lessons learned included the need for further strengthening of global surveillance systems, including animals; the need for improved vaccine technology and delivery to provide vaccines faster and more efficiently (particularly those vaccines not requiring refrigeration, for use in developing countries); and the usefulness of new media (including Twitter, Facebook, and YouTube) for disseminating important and useful messages to the community.

James Matthews from Sanofi Pasteur then provided an industry perspective on H1N1 vaccine development and deployment. Based on an avian virus outbreak in 1997, combined intelligence from the World Health Organization (WHO), various governments, and industry predicted that ‘the next pandemic’ would evolve from an avian H5N1 virus with origins in Southeast Asia. It was anticipated that the pandemic vaccine would likely be adjuvanted and probably require the administration of two doses in order to provide full protection. Surprisingly, the novel H1N1 virus appeared in April 2009 in North America, after it was assumed that subsequent pandemics would be of Southeast Asian and avian origin.

Despite the relatively short time from the 2009 H1N1 virus first being identified as a pandemic threat (April 2009) to the development and distribution of an H1N1 vaccine (September 2009), there is a continuing need to develop our capacity to shorten the duration to the first availability of the vaccine. To discuss new technologies in vaccine development, Jose Galarza of Technovax, Inc. discussed their efforts to develop a new way to produce highly immunogenic non-infectious monovalent and polyvalent influenza virus-like particle (VLP) vaccines. Improved production techniques have brought about many-fold increases in safe vaccine production without the need for inactivation, introducing the potential for higher yields in a reduced timeframe and at lower cost. Philip Dormitzer from Novartis Vaccines and Diagnostics then convened a panel discussion with all speakers.

Presented by

This event is part of the Dr. Paul Janssen Memorial Series at the New York Academy of Sciences.

source: NATURE