The role of influenza in the epidemiology of pneumonia.
Interactions arising from sequential viral and bacterial infections play important roles in the epidemiological outcome of many respiratory pathogens. Influenza virus has been implicated in the pathogenesis of several respiratory bacterial pathogens commonly associated with pneumonia. Though clinical evidence supporting this interaction is unambiguous, its population-level effects-magnitude, epidemiological impact and variation during pandemic and seasonal outbreaks-remain unclear. To address these unknowns, we used longitudinal influenza and pneumonia incidence data, at different spatial resolutions and across different epidemiological periods, to infer the nature, timing and the intensity of influenza-pneumonia interaction. We used a mechanistic transmission model within a likelihood-based inference framework to carry out formal hypothesis testing. Irrespective of the source of data examined, we found that influenza infection increases the risk of pneumonia by ~100-fold. We found no support for enhanced transmission or severity impact of the interaction. For model-validation, we challenged our fitted model to make out-of-sample pneumonia predictions during pandemic and non-pandemic periods. The consistency in our inference tests carried out on several distinct datasets, and the predictive skill of our model increase confidence in our overall conclusion that influenza infection substantially enhances the risk of pneumonia, though only for a short period.
Department of Ecology &Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.|Center for the Study of Complex Systems, University of Michigan, Ann Arbor, MI 48109, USA.|Department of Epidemiology, Johns Hopkins School of Public Health, Baltimore, MD 21205, USA.
Sourya
S
Shrestha
Department of Epidemiology, University of Michigan, Ann Arbor, MI 48109, USA.
Betsy
B
Foxman
Undergraduate Research Opportunity Program, University of Michigan, Ann Arbor, MI 48109, USA.
Joshua
J
Berus
Department of Epidemiology, University of Pittsburgh Graduate School of Public Health, Pittsburgh PA 15261, USA.
Willem G
WG
van Panhuis
Healthcare Cost and Utilization Project, Center for Delivery, Organization and Markets, Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services, Rockville, MD 20850, USA.
Claudia
C
Steiner
Division of International Epidemiology and Population Studies, National Institutes of Health, Bethesda, MD 20892, USA.
Cécile
C
Viboud
Odum School of Ecology, University of Georgia, Athens, GA 30602, USA.|Department of Infectious Diseases, School of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.|Fogarty International Center, National Institutes of Health, Bethesda, MD 20892, USA.
Pejman
P
Rohani
D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology* / Q000473:pathology / Q000821:virology; D016013:Likelihood Functions; D009975:Orthomyxoviridae / Q000472:pathogenicity; D011014:Pneumonia / Q000453:epidemiology* / Q000473:pathology / Q000821:virology