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Table 1 Comparison of the 1918–1919 and the 2009 H1N1 influenza pandemics

From: The first influenza pandemic in the new millennium: lessons learned hitherto for current control efforts and overall pandemic preparedness

  1918–1919 2009
Influenza virus Avian Influenza A H1N1 Swine-Origin-Influenza A(H1N1)v
Social and political Context World War I – U.S. troops being deployed to Europe One of the largest economic recessions in the U.S. with worldwide reach
   Globalization, ease of travel, population overgrowth, megacities
Source of viral strain emergence Historians have suggested to potential origins for this pandemic viral strain in China or in the Midwestern US military camps during World War I Unclear source, phylogeny of the virus demonstrates to be an Eurasian H1N1 swine strain
Seasonality and transmissibility Highly-transmissible – three succeeding waves of the outbreak Cases surfaced in early spring in Mexico City and in California, U.S.A.
  Initial wave spring 1918 with sustained multifocal transmission Sustained transmission (two generations) only in North America
Affected age groups Most deaths occurred within the first six months of the pandemic. Most deaths occurred within a three week time span.
  Most affected group 15–34 year-old population Most affected group is the 5 to 30; case-fatality rate has ranged from 5 to 45 years of age
Case management Insufficiency of healthcare systems Wider availability of healthcare institutions
  Absence of effective antimicrobials for treating secondary bacterial pneumonias. Availability of broad-spectrum antimicrobials for treating secondary bacterial pneumonias
  Medical intensive care in early phases of development Sophisticated medical intensive care and mechanical ventilatory support
  Insufficient infection control activities More established infection control activities and programs
Virulence Highly virulent Virulence only demonstrated as causing most fatalities in Mexico
Availability of vaccine No No
Susceptibility to antivirals No availability of antivirals Susceptibility to neuraminidase inhibitors (oseltamivir). However, there are growing number of resistant viral strains to oseltamivir
Nosocomial transmission Highly transmissible in hospital settings Possibility of nosocomial transmission under investigation with 81 healthcare workers affected in the U.S [23]
Molecular characterization H1N1 avian strain without evidence of reassortment (4) H1N1 (triple reassortant – human – avian – swine)
Natural history of the outbreak and outcomes More than 300 million cases worldwide By June 11, 2009, 74 nation states have cases, with approximately 27,737 confirmed cases and 141 death
  More than 50 million people deaths worldwide