Impact working group Intermeeting work group summary

1
Impact working groupInter-meeting work group
summary

• June 15-16, 2005
• Atlanta

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Disease impact workgroup goals

• Part I Describe impact of past pandemics on
  groups by age and underlying conditions
• Part II Determine whether data support
  sub-prioritization of high risk beyond current
  inter-pandemic tiering

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Participants

• Ted Eickhoff, UCHSC
• Paul Glezen, Baylor Coll. Of Med
• Marika Iwane, NIP, CDC
• Susan Lett, CSTE
• Megan Lindley, ASPH
• Arnold Monto, U. of Mich. School of Public Health
• Kathy Neuzil, ACP
• Ishmael Ortega-Sanchez, NIP, CDC

• David Shay, NCID, CDC
• Rich Schieber, NIP, CDC
• Ben Schwartz, NVPO
• Bill Thompson, NIP, CDC
• Pascale Wortley, NIP, CDC

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Assumptions

• Very limited antiviral supplysome high risk
  groups may be prioritized for prophylaxis or
  early therapy
• Vaccine production at rate of approximately 20
  million doses per month, necessitating
  sub-prioritization of high risk

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Part I a. Clinical Attack rates
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Influenza attack rates, 1918 (Frost 1919)
approximations based on figurehousehold surveys
conducted Dec 1918
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Attack rate by community, 1918 (Frost 1920)
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Clinical attack rates during Fall 1957
lab-confirmed
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Clinical attack rates Nov 1968-Jan 1969
weekly mean averages
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b. Death rates
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1918 PI death rates (Frost 1919)
approximations based on figure
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Age-Specific Influenza Death Rates Among Females
in England and Wales, 1918
?
Nguyen-Van-Tam, JS, et al. Vaccine, 2003
21762-68.
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PI death rates per 100,000 population, 108
cities, Aug-Dec 1957 (Dauer 1958)
Age group
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PI death rates per 100,000 population, 1968-69
(Luk 2001)
Age group
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c. Excess death rates
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1918 excess death rates (Luk 2001)
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Fall 1957 excess death rates
PI, compared to previous year All cause,
modeling PI, modeling
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1968 excess PI death rates (Luk 2001)
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Source Serfling 1967
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Age-specific excess mortality by pandemic
numbers and rates per 100,000 (Simonson 1998)
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Part II Sub-prioritizing
the high risk
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Specific conditions pregnancy

• 1918-19 and 1957-58 data are limited but suggest
  pregnant women were at increased risk of death
• 1968-69 no data on impact on pregnant women
• Interpandemic influenza pregnant women are high
  risk but not at higher risk than other high risk
  groups unless they have another underlying HR
  condition.

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Specific conditions bone marrow transplants

• Limited studies (Nichols 2004, Whimbey 1994) ,
  but both suggest high rates of complications.
• Largest study (Nichols) 18/62 BMT pts with lab
  confirmed influenza had LRI 6/62 died (5 of 6
  had LRI)
• Likely greater benefit from antiviral drugs than
  vaccine

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Hospitalizations and Deaths per 1,000
Unvaccinated Persons 65 1996-1998
Year 1 range 36-86 Year 2 range 36-56

Renal disease, immunodeficiency or receipt of
organ transplants, non hematologic cancer
Source Hak 2002 CID
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Hospitalizations and Deaths per 10,000 Persons
15-64 1973-1992
Range 36-76/10,000
Neuzil 1999 JAMA Neuzil 2003 JAIDS
NS
HIV-HAART data 1995-1999
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PI death rates 1968-69 and 72-73, by condition,
Oregon HMO, all ages combined (Barker 1982)
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Number of high risk conditions, Oregon HMO,
1968-69 and 1972-73 (Barker 1982)
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Previous hospitalization

• Fedson
• 39 to 46 of elderly discharged for
  influenza-associated respiratory conditions had
  recent hospitalization
• 62-67 of those who died had a recent
  hospitalization
• 6 of 65-74 (12 of 75) had a hospital
  discharge during vaccination season (Sept 1-Nov
  30)

Annals of Internal Medicine 1992116550-5
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Association of clinical characteristics with
hospitalization due to pneumonia or influenza and
death due to any cause, during the influenza
season among persons gt64 (Hak 2004)
Immunodeficiency and organ transplants
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Potential criteria for sub-prioritization of
high risk

• Age high mortality in lt1 in pandemics among
  adults increasing risk with age (18-49 vs 50-64)
• Number of high risk conditions.
• History of hospitalization for high risk
  condition or PI.
• Severe immunosuppression, e.g. BMT. -data not
  available for other immuno- compromised
  subpopulations.

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Inter-pandemic prioritization
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Size of specific groups
groups may overlap
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Potential subprioritization of high risk, cont

• Pro
• High risk within tiers are not equal,
  sub-prioritization could help target most
  vulnerable first as vaccination of some groups
  will take several months (e.g. gt40 million 2-64
  with HR)
• Con
• Implementation may be challenging
• Data are limited

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Extra slide
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Pregnancy

• Harris 1919 case series of pregnant women with
  influenza 50 had pneumonia, and 50 case
  fatality rate w/ pneumonia (7-9th months 60 vs
  1-6 m45-53).
• Woolston 1918 2154 pts admitted to Cook County
  Hospital 50 of pregnant women died compared
  with 33 of other pts.
• Greenberg 1958 NYC mortality data fall 195747
  PI deaths in women 15-49 22/47 (47) were
  pregnant women.