Influenza Other Respiratory Viruses
INTRODUCTION: Epidemiological studies of the 1957 influenza pandemic are scarce, particularly from lower-income settings.
METHODS: We analyzed the spatial-temporal mortality patterns of the 1957 influenza pandemic in Chile, including detailed age-specific mortality data from a large city, and investigated risk factors for severe mortality impact across regions.
RESULTS: Chile exhibited two waves of excess mortality in winter 1957 and 1959 with a cumulative excess mortality rate of 12 per 10 000, and a ~10-fold mortality difference across provinces. High excess mortality rates were associated with high baseline mortality (R(2) =41.8%; P=.02), but not with latitude (P>.7). Excess mortality rates increased sharply with age. Transmissibility declined from R=1.4-2.1 to R=1.2-1.4 between the two pandemic waves.
CONCLUSIONS: The estimated A/H2N2 mortality burden in Chile is the highest on record for this pandemic-about three to five times as severe as that experienced in wealthier nations. The global impact of this pandemic may be substantially underestimated from previous studies based on high-income countries.
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Chowell, G., Simonsen, L., Fuentes, R., Flores, J., Miller, M., & Viboud, C. (2016). Severe Mortality Impact of the 1957 Influenza Pandemic in Chile.. Influenza Other Respiratory Viruses, (). http://dx.doi.org/10.1111/irv.12439