Pandemic influenza and surge capacity

1
Pandemic influenza and surge capacity?

• Pandemic Influenza Exercise, 30th January 2008
• Dr Nick Phin
• Pandemic Flu Office
• Health Protection Agency, Centre for Infections
• Nick.phin_at_hpa.org.uk

2
Influenza epidemiology

• All ages affected
• especially children and elderly
• Duration of activity
• 6 10 weeks during winter period
• Morbidity
• Bronchitis and pneumonia (mainly in the elderly)
• Mortality
• 3000 4000 excess deaths per year
• 20,000 during high epidemic periods
• (mainly in the elderly)

3
Influenza A virus
N
N
H
H
(16)
(9)
Haemagglutinins are linked to infectiousness
Neuraminidases to viral release and dissemination
4
Circulating influenza strains in humans and
pandemics in 20th Century
H3N2
H2N2
H1N1
H1N1
1920 1940 1960 1980 2000
5
Viral pneumonia
6
Bacterial pneumonia
7

• I would not say that the future is necessarily
  less predictable than the past. I think the past
  was not predictable when it started
• Donald Rumsfeld

8
Pre-requisites for pandemic influenza

• PAN (all) DEMOS (people) an epidemic that
• affects all people
• New influenza A sub-type Haemagglutinin (H)
• unrelated to immediate (pre-pandemic)
• predecessor.
• Little or no pre-existing population immunity
• Causes significant clinical illness
• Efficient person-to-person spread

9
Overall clinical attack rate in previous pandemics
10
Age specific influenza death rates among females
in England Wales, 1st and 4th quarters of 1918
1957/1968
Death Rate per 1,000
Ministry of Health, GB, 1919
11
1918 Flu Excess mortality rates by major towns
Chris Lane Department of gastro-intestinal
infection Centre for Infections
12
1918 Flu Excess mortality rates by major towns
Chris Lane Department of gastro-intestinal
infection Centre for Infections
13
57/58 68/69 Pandemic
14
Defence in layers
Pandemic Specific Vaccine
Public Health Measures (hygiene masks
distancing infection control, etc.)
Pre-pandemic vaccine?
Antivirals
Antibiotics
15
Societal interventions

• Aims
• To minimise the mortality and morbidity
  associated with an influenza pandemic by
• delaying its arrival
• slowing its spread
• reducing the proportion of the population
  infected
• So as to
• minimise the impact at any one time
• allow more time for specific countermeasures such
  as immunisation

16
Pandemic vaccine

• It may take 4-6 months or longer to produce a
  vaccine
• Unlikely to be available during early stages of
  a pandemic
• Not enough for everybody production capacity
• Benefits of pre-pandemic vaccine?

17
Antiviral drugs

• 01 March 2005 Health Secretary John Reid
  announced the Department of Health was to procure
  14.6 million courses of oseltamivir (Tamiflu),
  an antiviral drug, as part of the UK's
  preparedness for an influenza pandemic. This has
  now been secured.
• Prevent the virus from reproducing and thus
• Reduce periods infectivity and symptom
• Prevent secondary complications and can reduce
  hospital admissions by 50
• But
• Must be taken within 48 hours of onset of
  symptoms
• Effectiveness in a pandemic is unknown (not
  100)
• May not be enough prioritising needed

18
Context

• The way care is delivered has changed and there
  is less resilience in the system
• Larger and more elderly population
• Increased public expectations
• Average District General Hospital may see in
  excess of 1000 extra admissions per week at the
  peak of the pandemic

19
RCGP Weekly Consultation Rate for Influenza and
Influenza-like Illness and changes to thresholds
Epidemic Activity
Higher than average seasonal activity
Epidemic Activity
Normal seasonal activity
Normal seasonal activity
Back
20
RCGP Consultation rates for Influenza England and
Wales
Prior to 1994 activity was recorded as epidemic
influenza and influenza-like illness. Data
for 1969/70 and 1975/76 represents a total of
these data for comparison with recent years.
21

• Surge capacity reflects the ability of the
  health service to expand beyond normal services
  to meet an increased demand for medical care.

22
Timing

• Use of three staged response
• Pre surge NHS preparation during UK Alert
  Levels 12 may be 7- 18 weeks long
• Surge increased activity to, and including
  peak, the trigger will be determined
  locally/regionally - 4-5 weeks
• Recovery Gradual return to normality

23
First wave
24
Elements of response

• Meeting demand
• Expand capacity
• Prioritise services
• Managing demand
• Prioritise patients and withhold treatments

25
Prioritisation of patients

• Across the spectrum of care using inclusion and
  exclusion criteria
• Evidence based
• Difficult ethical and professional tensions

26
What guidance can you expect?

• Operational guidance for Critical Care services
• Service Prioritisation Framework and
  implementation guidance document
• Admission and Discharge guidance document

27
Challenges

• Organisations having plans and process agreed and
  in place
• Refining the clinical categories and achieving a
  clinical understanding of them
• Public and professional buy in
• The alternative provision of care
• Indemnity