B - Planning for a Turkey Flu Pandemic

Transcription

1 RA Pandemic risk: B - Planning for a Turkey Flu Pandemic 8 B - Planning for a Turkey Flu Pandemic You are employed by the government OR service and your team has been asked to provide OR support for the UK Government Health Department. You have been asked to analyse the options for dealing with a new variety of flu, Turkey Flu, which is thought to be a hybrid of a human flu and an avian flu that infects turkeys. It has recently been reported to have started in Argentina, where it appears to be spreading fast and to have caused many deaths in Buenos Aires. Confirmed outbreaks and some deaths have also been reported in Brazil and Japan. At the moment there are no known cases in the UK, but it clearly possible that a dangerous world wide pandemic will develop. History of the Turkey Flu Outbreak The outbreak was first identified in Argentina on 26th of December This day will be referred to as day 1 of the outbreak (though it is likely that the outbreak really started before that). Further outbreaks were detected in Brazil on day 13 and in Japan on day 19. Currently it is day 63 and we have available data (in file pure3.txt) on the cumulative number of cases in these countries up to day 62. This is plotted in the graph below Argentina Brazil Japan Cumulative total or reported cases Days since first case

2 RA Pandemic risk: History of the Turkey Flu Outbreak 9 Other statistics on the outbreak: On average flu symptoms are lasting for 4 days. The numbers of deaths reported up to and including day 62 in Argentina, Brazil and Japan are 38, 30 and 7 respectively. On average it is taking 17 days after a person reports flu symptoms for death to occur. Blood serum antibody tests indicate that 15% of people are immune and there is no reason to believe this initial immunity will vary between countries. So far none of these countries have taken any measures to limit the spread of the infection. Population data: The world population is about and the populations of Argentina, Brazil, Japan and the UK are approximately , , and respectively. About 250,000 people enter the UK each day (and approximately the same number leave.)

3 RA Pandemic risk: Task B: Remit 10 Task B: Remit Newspapers have been speculating that Turkey Flu might lead to 400,000 deaths in the UK. In a week s time there will be the first meeting of a committee that has been appointed to manage the UK s response to the pandemic. You are asked to produce a written technical report of up to 9 pages for this meeting assessing the risks to the UK of a possible Turkey Flu pandemic and providing contingency plans for dealing with it in the UK. You will not attend the management committee meeting but the head of the UK Government OR group will attend, and your report should be aimed at him. The report should describe how to manage the risks and find some balance between the costs of preventative measures and the costs of the epidemic in terms of deaths and lost working days. Guidance is sought on the following issues: 1. How likely is it that Turkey Flu has already reached the UK and if it has how many infected people are already in the UK? 2. How many people with Turkey Flu are expected to arrive at the UK border each day as the pandemic develops. 3. What measures (if any) should be taken to prevent the epidemic starting in the UK and if it does what should be done to control it? 4. Should there be restrictions on travel into the UK? 5. How much Turkey Flu vaccine should be ordered and when should the orders be placed? 6. Should travel restrictions within the UK be imposed, and if so when? 7. Should throat swabs be used to monitor over time how many people are catching Turkey Flu? 8. Should blood serum antibody test be used to monitor over time the number in the population who are immune? 9. Should we run an advertising campaigns about hygiene measure to limit the spread of the flu? If so when?

4 RA Pandemic risk: Task B: Remit The major uncertainty is the detection rate. Assess what action is appropriate for the three scenarios of detection rate α = 0.1, α = 0.4 and α=0.75. On the assumption that the probability of these scenarios is 0.3, 0.5 and 0.2 respectively, develop a plan that takes into account this uncertainty. How can this uncertainty be reduced. (Groups of size two may use the first and third scenarios only and assume their probabilities are 0.6 and 0.4 respectively.) For assessing your plans calculate the actual and expected number of deaths and total economic costs to the economy excuding deaths, but use as your criterion for selecting the plan the combination of economic costs and costs associated with death using the NICE life value. Compare your plan with the situation where no control measures are taken. 11. What other major uncertainties and risks are there in your plans and what what can be done to reduce them?

5 RA Pandemic risk: Data, Costs, Preventative Actions and Assumptions 12 Data, Costs, Preventative Actions and Assumptions 1. Day 1, when first cases in Argentine were detected, was 26th December. Today is day 63 and the meeting to decide strategy will be on day In a typical year for normal seasonal flu there are about 6,000 deaths in the UK from flu, and in a bad year (such as ) there are about 20,000 deaths. 3. In previous flu epidemics the detection rate α has been between 0.1 and 1.0. Assume α for Turkey Flu will be in this range. Assume the Rt 0 is the same for anybody with Turkey Flu, whether or not Turkey Flu has been diagnosed, and everybody who dies because of it is known to have died of it. 4. Assume that from experience of previous flu epidemics it is expected that for Turkey Flu the UK winter R 0 level will similar to Japan s and the summer level will be similar to the Argentine level. Assume that the epidemic will grow in the rest of the world with a similar growth rate to Brazil. Assume summer in the northern hemisphere and winter in the southern hemisphere starts on 21st March (day 86) and winter (summer) starts on 21st September (day 270), and that there is no difference between summer and winter in Brazil. 5. Assume that the proportion of people arriving at the UK border with flu is the same as the proportion with flu in the rest of the world, and the proportion leaving with flu is the same as the proportion with flu in the UK. 6. The borders could be closed to people entering the UK. The cost to the economy is estimated at 100/person/day delayed. (Note this is cumulative: a person delayed 3 days incurs a financial cost 3 times bigger than if delayed 1 day.) 7. People entering the country could be scanned for high temperature and those with a high temperature could be quarantined until the results of a swab to detect Turkey Flu are known. Then those shown to have Turkey Flu could be quarantined until they have recovered. It is estimated that at any time 0.4% of the population who do not have Turkey Flu will have a temperature and other symptoms that are not distinguishable from Turkey Flu without a swab test. 8. The cost of taking a temperature at the borders is 1/person and the result is instant. The cost of a swab test is 66 and the results take 1 day.

6 RA Pandemic risk: Data, Costs, Preventative Actions and Assumptions The cost of quarantining each person at the borders will be 200/per day 10. The total cost to the economy of doing a blood serum test to find if a person has antibodies that makes him/her immune from Turkey Flu will be 85. It takes 3 weeks after a person has recovered for the antibodies to be measurable. 11. The UK government could sign a contract from a foreign supplier to buy some quantity of vaccine that is being developed against Turkey Flu. The cost of the vaccine will be 8 per dose and the cost to the economy of delivering it will be an additional 20. One dose will give immunity. It is estimated that 1 in 3m people given the vaccination will die as a result but that other side effects will be minor. Vaccine will available 200 days after ordering it. Several orders can be placed at different times. No more that 310,000 vaccinations can be done per day. 12. If given while a person has flu, an anti-viral drug reduces its severity. The person s basic reproduction number is reduced by 7% and his/her chance of dying is reduced by 10%. No side effects are expected. The cost of buying a course of antivirals for one person is 85 and the cost to the economy of delivering it will be 10. There is no limit on availability of antivirals 13. An advertising campaign costing 50m is expected to reduce R 0 t by 2% for a period of 60 days from its start. The campaign can be repeated later. 14. The government has an emergency plan to restrict travel and close schools. Its cost will be 500,000,000 per day and it is estimated it will reduce the average basic reproductive number by 25% on each day it is enforced. 15. The average cost to the economy of a person having flu is NICE (the UK government s advisory body on medical treatment) values a year of fully healthy life at 20,000-30,000. This is used when it is assessing whether the government should or should not pay for a treatment. Assume the upper figure and assume the healthy life expectancy is 80. [For a treatment that saves lives equally at all ages this is equivalent to valuing a life at about 1.2m. This is a lot less than 4.5m, which is the figure used by the US Environment Protection Agency.]