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Epidemiology and Surveillance: Lessons from Past Pandemics

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Source of Pandemic Viruses. Reassortment. 2 segments from Avian Virus. H3N2. 1968-1969 ... Pandemic Years. Effects of Past Pandemics on the US. Source: NVPO. ... – PowerPoint PPT presentation

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Title: Epidemiology and Surveillance: Lessons from Past Pandemics


1
Epidemiology and Surveillance Lessons from Past
Pandemics
  • Arnold S. Monto, MD
  • Professor of Epidemiology
  • University of Michigan School of Public Health
  • Founding Director
  • University of Michigan Bioterrorism Preparedness
    Initiative
  • Ann Arbor, MI

2
Basic Questions
  • When will the virus arrive and spread? How long
    from the source?
  • What will the principal age and other risk groups
    be?
  • How many will be affected?
  • Morbidity?
  • Mortality?

3
Source of Pandemic Viruses
4
Effects of Past Pandemics on the US
Source NVPO.
5
The 1918 Pandemic in Asia and Africa
Influenza-Associated Deaths
  • Asia
  • India 12.5 million deaths (higher than bubonic
    plague)
  • Japan 257,000 deaths
  • Rest of Asia 3,000,000 deaths
  • Africa
  • Union of South Africa 139,471 deaths out of
    6,100,000 population
  • Madagascar 114,000 deaths out of 3,250,000
    population

Jordan, ED. Epidemic Influenza, AMA. Chicago,
1927.
6
Review of Past Pandemics
  • Age Specificity
  • Traditional view U or J shaped curves in
    most pandemics W shaped curve in 1918.
  • Variations 1889-1890Reports from UK of high
    mortality in young adults
  • Sparing of elderly in 1918
  • Relatively higher death rates in young adults
    in more recent pandemics
  • Will past history predict the future?

7
Pneumonia and Influenza Mortality in Influenza
Pandemics
Modified from Dauer Serfling. Am Rev Resp Dis.
1961 8315-28.
8
Age-Specific Influenza Death Rates Among Females
in England and Wales, 1918
?
Nguyen-Van-Tam, JS, et al. Vaccine.
200321762-68.
9
1957
10
Influenza Attack Rates by Age in Tangipahoa
Parish, Louisiana August, 1957
Langmuir AD. Am Rev Resp Dis. 1961835.
11
1968
12
Weekly Incidence of Influenza-like Diseasesin
Hong Kong June to September 1968
June
July
Aug.
Sept.
Week Ending
Cockburn et al. Origin and progress of the
1968-69 Hong Kong Influenza epidemic. Bull. Wld
Hlth Org. 196941345-8.
13
Peak Influenza Activity in the US by State and
Week 1968-69
Oct.
Nov.
Dec.
Jan.
Feb.
Week Beginning
Sharrar RG. National Influenza Experience in the
USA, 1968-69. Bull. Wld Hlth Org. 196941361-6.
14
Number of Episodes of Illness, Healthcare,
Utilization, and Death Associated with Moderate
and Severe Pandemic Influenza Scenarios
Estimates based on extrapolation from past
pandemics in the United States. Note that these
estimates do not include the potential impact of
interventions not available during the 20th
century pandemics. Source NVPO.
15
Conclusions
  • The 1918 outbreak was unique in terms of numbers
    of persons involved and age groups affected.
    There is a question as to whether 1889-90
    affected young adults disproportionately.
  • It is difficult from historic records to document
    the presence or effect of the 1918 virus before
    the second wave. Once that wave began, it
    spread quickly.
  • The 1957 virus probably spread for at least 6
    weeks in China, starting in February, before
    emerging. It affected South America before
    spreading to North America in the early autumn.
  • The spread of the 1968 virus was well documented
    from Hong Kong in July. The peak in the US was
    December-January.
  • Numbers affected in the future will be based on
    multiple factors currently unknown, and any
    estimates must be viewed as provisional.
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