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XIXth International Association of Gerontology and Geriatrics World Congress, Paris, France, July 6-8, 2009

Dr. Elena Naumova and Dr. Steve Cohen presented their work at the 19th IAGG World Congress.

Cohen SA, Wenger JB, and Naumova EN. Intergenerational transmission of influenza to seniors: Vaccination and grandparental caregiving

Abstract:
A small, but growing body of evidence indicates that annual vaccination of children against influenza not only provides a direct benefit to children by reducing influenza-associated morbidity and mortality in children, such vaccination may also impart herd immunity to the adult population by stemming influenza transmission from children to adults, particularly to vulnerable seniors. The study’s objective is to evaluate the effect of vaccinating children against influenza as a strategy to reduce influenza-related morbidity in seniors. In addition, this study will also assess whether increased physical contact between grandparents and their grandchildren through grandparental caregiving increases the likelihood of seniors contracting influenza and associated diseases. We abstracted over 14 million hospitalization claims for influenza or pneumonia using ICD-9CM codes 480-487 from the Centers for Medicare and Medicaid Services Medicare Part B database for the years 1991-2004,  classified into influenza season (July-June), and estimated yearly rates of influenza-associated disease. These rates were compared to grandparental caregiving levels from the US Census, and immunization coverage rates in children from the National Immunization Survey for all US counties over the 13 influenza season period. Grandparental caregiving was associated consistently with increased influenza-associated hospitalization rates in the elderly, especially in the younger elderly population, who may, in fact, be more likely to provide care for their grandchildren than older seniors. Vaccination coverage in children was inversely associated with influenza-associated hospitalization levels in seniors, particularly in the oldest seniors. Based on these observed associations, there is suggestive evidence to support the potential for influenza and pneumonia to be readily transmitted from children to older adults. Strategies to address seniors at the highest risk of contracting potentially deadly influenza may involve targeting children for influenza vaccination, along with grandparents who provide care for their grandchildren.

Naumva E, Castronova D, Fefferman N, Cohen S, Wenger J Naumov Y, Gorski J. Traveling waves and percolations in influenza transmission among United States elderly

The origin and spread patterns of seasonal influenza are still poorly understood. Seasonal waves of influenza travel over large spaces covering many climatic zones in a relatively short period of time arriving in late fall to early winter and dissipating in spring. Annual epidemics begin abruptly, peak within two to three weeks, and last from five to ten weeks and the precise mechanism for such patterns are unknown. Methods and Materials. We explored the influenza spatio-temporal dynamics in US older adults (65 years old or above) for thirteen seasons (1991-2004) in 2,974 US counties utilizing over fifteen million Medicare hospitalization records. We also abstracted monthly records for minimum ambient temperature from over 380 monitoring stations. Results. Comprehensive dynamic mapping of weekly influenza hospitalization rates reveals that: a) while different regions of the US can host the first outbreaks, influenza emerges predominantly in rural, aging, or highly transient communities; and b) while initial outbreaks are just as likely in the south as in the north, the intensity of northern outbreaks is associated with preceding drops in ambient temperature. We observed synchronization in influenza transmission in a unique pattern when influenza cases emerged in multiple sites, then appeared in adjacent areas or percolated within one area, and then in a period of one week resulted in a large multi-site outbreak. Conclusion. The proposed methodology for generating dynamic maps in real time on a refined spatial scale along with supporting environmental and socio-economic information provides valuable information, which has a strong potential for facilitating preparedness of public health workers to mitigate influenza outbreaks on local, regional, and national levels. Furthermore, a better understanding of influenza seasonality provides insights for many aspects of influenza including pathogenesis, viral evolution, transmissibility, vaccination efficacy, and treatment options, especially for the frailest subpopulations.

The two conference proceedings can be found in The Jounral of Nutrition, Health and Aging. Volume 13 (supp 1) published in June 2009.