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Pandemic H1N1 Influenza: Where Are We Now, and Where Will We Be in the Fall

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Flu B strain changed, others same. Now 83% are recommended vaccine. Last year ... 'Swine Flu' parties. Can get really sick. More dangerous than vaccine. Summary ... – PowerPoint PPT presentation

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Title: Pandemic H1N1 Influenza: Where Are We Now, and Where Will We Be in the Fall


1
Pandemic H1N1 Influenza Where Are We Now, and
Where Will We Be in the Fall?
  • Steven Lawrence, MD, MSc
  • Associate Director-Emergency Response Planning,
    MRCE
  • Division of Infectious Diseases
  • Washington University School of Medicine
  • PandemicPrep.org
  • July 28, 2009

2
Disclosure Statement
  • No Conflicts of Interest

3
Outline
  • Where is H1N1 now?
  • How is H1N1 different?
  • H1N1 antiviral therapies
  • H1N1 vaccine

4
  • Where is H1N1 Now?

5
Pandemic H1N1 Origin
  • What we know about origin
  • First human cases in Mexico
  • Probably started in March
  • Genetic material from pigs gt birds gt humans
  • How novel is it?
  • Seasonal H1N1 circulating since 1977
  • H1 component very different
  • Acts like a brand new virus ? pandemic
  • May be more similar to 1918 than seasonal

6
Flu Viruses Currently in Play
  • Seasonal
  • Influenza A/H1N1
  • Influenza A/H3N2
  • Influenza B
  • Pandemic H1N1 (swine)
  • Avian influenza H5N1
  • Will there be strain replacement?

7
H1N1 Reaches Pandemic Status
  • Definition of pandemic
  • Extent, not severity
  • Sustained community level outbreaks in multiple
    regions
  • Current WHO classification
  • Phase 6, Moderate severity
  • From unknown to pandemic in 6 weeks
  • Declaration on 6/11
  • Prior pandemics took 6 months

8
Global H1N1 (as of 7/24/09)
  • 160 countries
  • gt143K lab-confirmed cases
  • Rapid rise in U.K. worst flu in decade
  • Ramping up in Africa, SE Asia
  • gt800 deaths
  • Median age 12-17
  • Recently trending upwards

9
U.S. H1N1 Activity (7/24/09)
  • 99 of all H1N1 sub-typed
  • 43,771 lab-confirmed cases
  • No longer counting
  • Underestimates true numbers
  • Waste of PH resources
  • Goal monitor morbidity/mortality/unusual
  • 302 deaths
  • 27/95 total flu pediatric deaths
  • Still transmitting in summer
  • Canada, Europe, US, Japan
  • Summer camp military outbreaks

10
CDC Assumptions
  • Scenario - no effective vaccine
  • 40 infected by 2011 (2 seasons)
  • 10-15 most years
  • gt100,000 deaths
  • Typically 36,000
  • 70,000 in 1957
  • Already gt1M cases

11
  • How is H1N1 Different?

12
Pandemic H1N1 Clinical Features
  • Very similar to seasonal flu
  • Children/adolescents are reservoir
  • 60 of cases lt18y.o.
  • Can have severe neuro complications
  • Symptoms
  • Fever may be less universal
  • Sore throat
  • Runny nose, cough
  • Headache, muscle aches
  • Severity
  • Mortality 0.0006-0.15
  • Risk factors for severe disease
  • Underlying medical conditions - asthma
  • Pregnancy

13
Pandemic H1N1 Clinical Features
  • Key potential differences from seasonal flu
  • Persons gt65yo lower than expected risk
  • 33 with residual immunity
  • Symptoms more likely GI (25)
  • Possibly more infectious
  • Secondary attack rate 20-25 vs. 10-15
  • Possibly more severe in young people
  • 2 hospitalized, especially age 30-44
  • Might be increased risk flu pneumonia
  • Secondary bacterial infections rare
  • Obesity and gender (M) may be a risk factor

14
Pandemic H1N1 Transmission
  • Just like seasonal flu
  • Person-to-person
  • Has now become a human pathogen
  • Still has potential to infect pigs
  • Pork products not at risk

15
Preventing Transmission
  • Basic strategy avoid contact with virus
  • Keep sick people away
  • Personal hygiene/etiquette
  • Personal Protective Equipment (PPE)
  • Environmental cleaning
  • Social distancing measures

16
Where Will It Go From Here?
  • Worrisome factors
  • Young people seem to do worse
  • 1918 started mild and returned severe
  • Effective vaccine months away
  • Easily transmits between humans
  • Swine origin may more easily allow infection and
    subsequent reassortment in pigs
  • Increased attack rate but same mortality could
    still double or triple total deaths

17
Where Will It Go From Here?
  • Reassuring factors
  • Relatively mild disease so far
  • Low mutation rate thus far
  • Virulence, vaccine efficacy, antiviral resistance
  • Vaccine should be available
  • Neuraminidase inhibitors work
  • Will it be a strain replacement with a couple
    bad years, or 1918-like?

18
  • H1N1 Antiviral Therapies

19
Antiviral Medications
  • Adamantanes
  • Amantidine
  • Rimantidine
  • Neuraminidase inhibitors
  • Zanamavir (Relenza)
  • Oseltamivir (Tamiflu)
  • Peramivir

Moscona, N Engl J Med 20053531363
20
Antiviral Resistance
  • Becoming more complicated all the time

21
Pandemic H1N1 Resistance
  • Oseltamivir resistance
  • 5 cases
  • Mostly while on prophylaxis
  • 1 not on therapy
  • All sensitive to zanamivir
  • No subsequent spread
  • Will see more
  • Inherently resistant to adamantanes

22
Antiviral Issues
  • Are they safe enough?
  • Oseltamivir (Tamiflu)
  • Neuropsychiatric side effects
  • Strange adolescent behaviors
  • Zanamavir
  • Challenging to use
  • Airway spasms cant use with asthma/COPD
  • Both pregnancy category C
  • Oseltamivir recommended by CDC

23
Antiviral Issues
  • Should businesses/individuals stockpile?
  • In most medical circumstances a bad idea
  • Safety concerns
  • Inappropriate usage breeds more resistance
  • Personal supplies being considered
  • Home MedKit
  • State/Federal stockpile (SNS)
  • Approximately 25 population
  • Earmarked for treatment only
  • Cannot be used for prophylaxis

24
  • H1N1 Vaccine

25
Seasonal Flu Vaccine 2009-10
  • Key recommendation changes
  • All kids 6mo-18y
  • Flu B strain changed, others same
  • Now 83 are recommended vaccine
  • Last year lt40 immunized
  • 6 products approved
  • 119M anticipated inventory
  • Give ASAP to clear way for H1N1
  • Reduce overall flu burden
  • Seasonal flu is still dangerous
  • Vaccinated individuals with ILI more likely to
    respond to oseltamivir
  • Early evidence H3N2 drifting

26
Pandemic H1N1 Vaccines
  • Production
  • Sanofi-Pasteur, Novartis, CSL Ltd, GSK, MedImmune
  • Poor yields (lt40) except MI
  • Using existing egg-based technology
  • Parameters being tested
  • Dose 7.5, 15, 30 mcg 3.75, 7.5 adjuvanted
  • 1 vs 2 doses (21 days)
  • Canada testing egg allergy
  • Concomitant seasonal
  • Compete or adjuvant effect?
  • Data some Sept., most Dec., kids Feb.

27
H1N1 Vaccine Uncertainties
  • Efficacy
  • Safety (likely to be safe as seasonal)
  • When/quantity available
  • Precise priority groups
  • How much demand will there be?
  • Distribution system
  • FDA approval process
  • Annual strain change model (non-adjuvanted only)
  • Emergency Use Authorization
  • Global ethics
  • Developed world buys it all
  • Non-use of adjuvants

28
H1N1 Vaccine Issues
  • SLU is recruiting
  • 314-977-6333
  • vaccine_at_slu.edu
  • Prioritization
  • May be decided tomorrow
  • Likely target groups (WHO recommendation)
  • HCWs
  • Underlying health problems
  • Children
  • Swine Flu parties
  • Can get really sick
  • More dangerous than vaccine

29
Summary
  • Witnessing history birth of a pandemic
  • Still numerous uncertainties
  • Severity
  • Vaccine availability/effectiveness
  • Antiviral resistance
  • At minimum, expect lot of cases and impact on
    workforce

30
(No Transcript)
31
Questions???
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