Demographic Shift of Influenza A(H1N1)pdm09 during and after Pandemic, Rural India

The Study

Conclusions

Acknowledgment

References

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Table 2

Suggested Citation

Shobha Broor

, Wayne Sullender, Karen Fowler, Vivek Gupta, Marc-Alain Widdowson, Anand Krishnan, and Renu B. Lal

Author affiliations: All India Institute of Medical Sciences, New Delhi, India (S. Broor, A. Kirshnan); University of Alabama, Birmingham, Alabama, USA (W. Sullender, K. Fowler); The Inclen Trust International, New Delhi (V. Gupta); and Centers for Disease Control and Prevention, Atlanta, Georgia, USA (M.-A. Widdowson, R.B. Lal)

Abstract

Population-based active surveillance in India showed higher incidence rates for influenza A(H1N1)pdm09 among children during pandemic versus postpandemic periods (345 vs. 199/1,000 person-years), whereas adults had higher rates during postpandemic versus pandemic periods (131 vs. 69/1,000 person-years). Demographic shifts as pandemics evolve should be considered in public health response planning.

Influenza epidemics and pandemics has been recognized for centuries (1,2), and the effects that influenza can have on public health infrastructure were demonstrated globally during the 2009–2010 pandemic (3). The dynamics of influenza transmission are dependent on many factors, including probability of infection, susceptible populations within age groups, and close contacts between susceptible and infected persons (4,5). Data from 3 recent influenza pandemics show that school-aged children have the highest disease rates and may serve as a key source of transmission to adults (2,6–8).
A recent mathematical modeling study suggested that initial exposure to a novel influenza virus among a highly susceptible population (school-aged children) results in a shift in transmission patterns as infection spreads, with adults more affected during later phases (9). To investigate if transmission of influenza A(H1N1)pdm09 (pH1N1) followed this demographic shift pattern, we examined comprehensive weekly active community surveillance for febrile acute respiratory illness (ARI) in 3 rural villages in northern India, as well as available extensive epidemiologic data.