Title: Pandemic preparedness: What can epidemiological modelling offer policy?
1Pandemic preparednessWhat can epidemiological
modelling offer policy?
- Nim Arinaminpathy
- Department of Zoology
- University of Oxford
2Talk plan
- Influenza a background
- From today to emergence of a novel influenza
virus - Antiviral drugs for control of pandemic influenza
3Influenza
- RNA virus
- Clinical manifestations
- Headache, sore throat, chills, fever,
- myalgia, anorexia, malaise
- Transmission
- By contact with respiratory droplets,
- generated by coughing or sneezing
- Infectiousness
- can start a day before symptoms and continue for
3 5 days after symptoms developing in adults
4The seasonal influenza burden
- Disease
- 5 15 of population affected with upper
respiratory tract infections in annual flu
season - Estimated 3-4,000 annual deaths in UK caused by
influenza infection (mainly elderly and
immunocompromised) - The Economy
- Europe flu accounts for 10 of sick leave
- Costs US estimated 90bn a year
5Influenza family tree
Orthomyxoviridae
Influenza
From http//www.abc.net.au/health
A
B
C
Type
H1N1
Subtype
H3N2
6Pandemic and seasonal influenza
Taken from www.en.influenza.pl
7Social and economic disruption
8Social and economic disruption
9H5N1 Future pandemic?
- Wild bird reservoir ? Poultry ? Humans
- Transmitted from bird to human by inhaling dried
aerosolised faeces - First major outbreak in 1997, Hong Kong
- Resurgence in 2003 has seen virus established in
poultry in South-East Asia - So far human-to-human spread is non-existent or
very limited - 387 human cases, 245 deaths to date
- Wide geographical spread, from S.E.Asia (inc.
Indonesia, Viet Nam) to Africa (Nigeria, Egypt) - However, H7N7 and N9N2 are also pandemic
candidates
10Evolution and emergence of pandemic influenza
- Each human case is an opportunity for an avian
virus to adapt for human transmission
11Antiviral drugs for pandemic control
- No vaccine for at least first 6 months
- Oseltamivir (Tamiflu) is main antiviral drug of
choice - UK stockpile
- Currently enough for 25 of population
- Drugs intended mainly for treatment, not
prophylaxis - For all clinical cases
- How best to minimise epidemic size and impact
with a limited stockpile? -
12A simple compartmental model
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13A simple compartmental model
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141957 Asian Flu pandemic
30/11/57
22/02/58
151957 Asian Flu pandemic
161957 Asian Flu pandemic
171957 Asian Flu pandemic
CFR 0.16 R0 1.65
25 stockpile exhausted
18How many drugs are needed?
Secondary effect of mass antiviral treatment is
to reduce the spread of infection in the
community Its strength depends on drug
efficacy and disease transmissibility
19Antiviral programmes
- By shortening infectious period and reducing
infectiousness, antiviral drugs can influence the
course of infection - Broadening and delaying epidemic peak
- Reducing numbers of cases
- If there is a risk-group for whom the drug has
little protective effect, the stockpile is better
deployed in the general population. - Priority shifts to protection from infection
rather than from illness.
20The social element
- Potential wastage of drugs on the worried well
- Personal stockpiles
- Non-compliance with treatment regime may lead to
drug resistance - Pressing ethical questions, eg distributive
justice
21Conclusions
- Mathematical models can offer valuable insights
into disease control - Transmission dynamics are often fundamental to
epidemic outcomes and effects of interventions - sometimes offering counterintuitive results!
- However models always entail simplifications,
often about human behaviour (important factors) - Effective pandemic preparedness could involve a
synergy between such models and the social
sciences