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1. Age-Specific Mortality During the 1918 Influenza Pandemic: Unravelling the Mystery of High Young Adult Mortality.

Author

Gagnon, Alain, Miller, Matthew S., Hallman, Stacey A., Bourbeau, Robert, Herring, D. Ann, Earn, David JD., and Madrenas, Joaquín

Subjects
INFLUENZA pandemic, 1918-1919, AGE factors in disease, YOUNG adults, MORTALITY, IMMUNOREGULATION, POPULATION biology, EPIDEMIOLOGY
Abstract

The worldwide spread of a novel influenza A (H1N1) virus in 2009 showed that influenza remains a significant health threat, even for individuals in the prime of life. This paper focuses on the unusually high young adult mortality observed during the Spanish flu pandemic of 1918. Using historical records from Canada and the U.S., we report a peak of mortality at the exact age of 28 during the pandemic and argue that this increased mortality resulted from an early life exposure to influenza during the previous Russian flu pandemic of 1889–90. We posit that in specific instances, development of immunological memory to an influenza virus strain in early life may lead to a dysregulated immune response to antigenically novel strains encountered in later life, thereby increasing the risk of death. Exposure during critical periods of development could also create holes in the T cell repertoire and impair fetal maturation in general, thereby increasing mortality from infectious diseases later in life. Knowledge of the age-pattern of susceptibility to mortality from influenza could improve crisis management during future influenza pandemics. [ABSTRACT FROM AUTHOR]

Published
2013
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2. Age-Specific Mortality During the 1918 Influenza Pandemic: Unravelling the Mystery of High Young Adult Mortality

Author

Alain Gagnon, Matthew S. Miller, Joaquín Madrenas, Robert Bourbeau, D. Ann Herring, David J. D. Earn, Stacey Hallman, and Digard, Paul

Subjects
Male, Aging, Viral Diseases, Epidemiology, Economics, lcsh:Medicine, Adaptive Immunity, Social and Behavioral Sciences, Sociology, Pandemic, 80 and over, 2.2 Factors relating to the physical environment, Aetiology, Young adult, lcsh:Science, Child, Aged, 80 and over, Economic History, Multidisciplinary, Mortality rate, Age specific mortality, virus diseases, Middle Aged, Biological Anthropology, Infectious Diseases, Child, Preschool, Pneumonia & Influenza, Human mortality from H5N1, Medicine, Female, Infection, Human, Research Article, Adult, Canada, medicine.medical_specialty, Adolescent, General Science & Technology, Mechanisms of Resistance and Susceptibility, Immunology, and over, Microbiology, Virus, Vaccine Related, Young Adult, Age Distribution, Clinical Research, Biodefense, Virology, Death Rate, Influenza, Human, medicine, Humans, Preschool, Biology, Immunity to Infections, Pandemics, Demography, Aged, Population Biology, business.industry, Prevention, lcsh:R, Immunity, Infant, Newborn, Infant, Influenza pandemic, Newborn, Influenza, United States, Good Health and Well Being, Emerging Infectious Diseases, Anthropology, Humoral Immunity, lcsh:Q, business
Abstract

The worldwide spread of a novel influenza A (H1N1) virus in 2009 showed that influenza remains a significant health threat, even for individuals in the prime of life. This paper focuses on the unusually high young adult mortality observed during the Spanish flu pandemic of 1918. Using historical records from Canada and the U.S., we report a peak of mortality at the exact age of 28 during the pandemic and argue that this increased mortality resulted from an early life exposure to influenza during the previous Russian flu pandemic of 1889-90. We posit that in specific instances, development of immunological memory to an influenza virus strain in early life may lead to a dysregulated immune response to antigenically novel strains encountered in later life, thereby increasing the risk of death. Exposure during critical periods of development could also create holes in the T cell repertoire and impair fetal maturation in general, thereby increasing mortality from infectious diseases later in life. Knowledge of the age-pattern of susceptibility to mortality from influenza could improve crisis management during future influenza pandemics.

Published
2013

3. Excess Mortality Associated with Influenza Epidemics in Portugal, 1980 to 2004

Author

Ausenda Machado, Helena Rebelo-de-Andrade, Mark A. Miller, Cécile Viboud, Baltazar Nunes, Paulo Nogueira, and Corinne M. Ringholz

Subjects
Viral Diseases, Pediatrics, Non-Clinical Medicine, Databases, Factual, Epidemiology, lcsh:Medicine, Global Health, Social and Behavioral Sciences, medicine.disease_cause, Influenza A Virus, H1N1 Subtype, Sociology, Influenza A virus, Medicine, Young adult, lcsh:Science, Child, Epidemiological Methods, Aged, 80 and over, Excess mortality, Multidisciplinary, Mortality rate, Statistics, virus diseases, Middle Aged, Infectious Diseases, Child, Preschool, Human mortality from H5N1, Public Health, Seasons, Research Article, Adult, medicine.medical_specialty, Adolescent, Influenza epidemics, Biostatistics, Infectious Disease Epidemiology, Virus, Young Adult, Population Metrics, Environmental health, Death Rate, Influenza, Human, Humans, Statistical Methods, Biology, Demography, Aged, Health Care Policy, Models, Statistical, Population Biology, Portugal, business.industry, Influenza A Virus, H3N2 Subtype, lcsh:R, Infant, Newborn, Health Risk Analysis, Infant, medicine.disease, Influenza, Pneumonia, lcsh:Q, business, Mathematics
Abstract

BACKGROUND: Influenza epidemics have a substantial impact on human health, by increasing the mortality from pneumonia and influenza, respiratory and circulatory diseases, and all causes. This paper provides estimates of excess mortality rates associated with influenza virus circulation for 7 causes of death and 8 age groups in Portugal during the period of 1980-2004. METHODOLOGY/PRINCIPAL FINDINGS: We compiled monthly mortality time series data by age for all-cause mortality, cerebrovascular diseases, ischemic heart diseases, diseases of the respiratory system, chronic respiratory diseases, pneumonia and influenza. We also used a control outcome, deaths from injuries. Age- and cause-specific baseline mortality was modelled by the ARIMA approach; excess deaths attributable to influenza were calculated by subtracting expected deaths from observed deaths during influenza epidemic periods. Influenza was associated with a seasonal average of 24.7 all-cause excess deaths per 100,000 inhabitants, approximately 90% of which were among seniors over 65 yrs. Excess mortality was 3-6 fold higher during seasons dominated by the A(H3N2) subtype than seasons dominated by A(H1N1)/B. High excess mortality impact was also seen in children under the age of four years. Seasonal excess mortality rates from all the studied causes of death were highly correlated with each other (Pearson correlation range, 0.65 to 0.95, P0.64, P

Published
2011