1. Bogota workshop on health services pandemic preparedness Dr. Oscar J Mújica; DPC/PAHO Bogota; COLOMBIA April 19-21, 2006 Pandemic Impact Assessment

2. pandemic influenza is a real & serious disease… Hien TT et al., New England J Med 2004;350:1179-1188 DAY 5 DAY 7 DAY 10 Bogota workshop on health services pandemic preparedness

3. the modeling problem influenza pandemics in 20 th Century: 1918; 1957; 1968 massive & notable impacts experts predict another pandemic: can not reliable predict when can not reliable predict how, who, where plan for next pandemic: it is a global health priority need numbers Bogota workshop on health services pandemic preparedness

4. PAHO/CDC pandemic impact assessment workshops to estimate the burden of disease attributable to influenza pandemic: excess of deaths, hospitalizations, and outpatient visits to evaluate the response capacity (i.e., the potential to cope with excess demand) from hospitals and outpatient health facilities (surge capacity) to estimate the magnitude of the loss of workdays to derive gross estimates of direct economic impact attributable to pandemic influenza Bogota workshop on health services pandemic preparedness

5. FluSoftware: FluAid, FluSurge & FluWorkLoss Bogota workshop on health services pandemic preparedness

6. 1957-58 influenza pandemic: geographic spread 02/57 04/57 06/57 05/57 06/57 07/57 08/57 06/57 07/57 C.W. Potter, Textbook of Influenza, 1998 Bogota workshop on health services pandemic preparedness

7. FluSoft modeling data & assumptions Bogota workshop on health services pandemic preparedness default values: US national estimates; CDC's Advisory Committee on Immunization Practices, ACIP

8. FluSoft modeling data & assumptions Bogota workshop on health services pandemic preparedness

9. FluSoft modeling data & assumptions Bogota workshop on health services pandemic preparedness other assumptions: employment & marriage rate

10. ? 01/19 03/18 04/18 06/18 05/18 06/18 ? C.W. Potter, Textbook of Influenza, 1998 1918-19 influenza pandemic: geographic spread Bogota workshop on health services pandemic preparedness

11. FluSoft modeling data & assumptions Bogota workshop on health services pandemic preparedness Locales, all US: 1 (New London; Baltimore; Maryland); 2 (Macon; Spartanburg; San Antonio; Augusta; Des Moines; Little Rock; Louisville); 3 (San Francisco) Frost WH. Public Health Reports 1920;35:584-97

12. FluSoft modeling data & assumptions Bogota workshop on health services pandemic preparedness The scaling factor was obtained by comparing the calculated death rates, by age group, from estimates of death for the U.S. population

13. estimated pandemic impact in the world clinical attack rate = 35%; first pandemic wave (8 weeks) * Ideally, be hospitalized ** Ideally, see a medical doctorDr. M. Meltzer, CDC; personal communication Bogota workshop on health services pandemic preparedness

14. estimated pandemic impact in the US Source: U.S. Dept Health and Human Services Pandemic Influenza Plan: Part 1. Page 18. Available at: http://www.dhhs.gov/pandemicflu/plan/pdf/part1.pdf Bogota workshop on health services pandemic preparedness

15. estimated potential impact in LAC clinical attack rate = 25%; first pandemic wave (8 weeks) FluAid/FluSurge modeling – Pandemic Impact Subregional Workshops Nov/Dec 2005 Bogota workshop on health services pandemic preparedness

16. estimated potential impact in LAC Clinical Attack rate = 25%; first 8-week pandemic wave Bogota workshop on health services pandemic preparedness

17. Latin America & the Caribbean: distribution of hospital admission excess Latin America & the Caribbean: distribution of hospital admission excess (AT25%; scenario 1968; 1 st pandemic wave) Bogota workshop on health services pandemic preparedness

18. Latin America & the Caribbean: potential pandemic impact on health services Latin America & the Caribbean: potential pandemic impact on health services (AT25%; scenario 1968; 1 st pandemic wave) Bogota workshop on health services pandemic preparedness

19. Latin America & the Caribbean: workdays loss attributable to influenza pandemic Bogota workshop on health services pandemic preparedness

20. Latin America & the Caribbean: costs from workdays lost due to pandemic influenza Bogota workshop on health services pandemic preparedness

21. Latin America & the Caribbean: non-discounted value of human life lost due to influenza pandemic ($ppp) direct cost from excess hospitalization (ICU & non-ICU) and excess outpatient visits has not yet been summarized. Bogota workshop on health services pandemic preparedness

22. on estimations… they are PRELIMINARY, and EXPLORATORY they are ILLUSTRATIVE they are NOT PREDICTIONS of what inevitably may happen they should serve as an AID IN PLANNING Bogota workshop on health services pandemic preparedness

23. Dr. Oscar J Mújica; DPC/PAHO Bogota; COLOMBIA April 19-21, 2006 a primer on transmission dynamics (or how pandemic influenza will move among us…)

24. what good are models…? first, because life is full of choices, risks, uncertainty, and trade-offs then, because we do need to make sound decisions in a setting of absence of absolute certainty (and we do need a rationale for them) and then because sound decisions demand evidence, structure, consistency, and simplification: models illustrate level of knowledge models show how we think things are connected and happen models add simplification = helps clarify models can help identify what is “most important” sensitivity analyses, confidence intervals no single answer Bogota workshop on health services pandemic preparedness

25. DAY CASES first case outbreak detection & response Bogota workshop on health services pandemic preparedness detection/ report laboratory confirmation response opportunity for control

26. DAY CASES opportunity for control first case detection report laboratory confirmation response timely outbreak detection & response Bogota workshop on health services pandemic preparedness

27. pandemic spread potential 0 1,000 2,000 3,000 4,000 5,000 cases 1 234 5 time What must happen at time 4 for this event to continue be seen as a public health problem? Basically, an equal number of incident (new) cases must be generated in the population per unit time… In other words, the ‘goal’ for each new case at time t is “to infect one” up to time t+1 Bogota workshop on health services pandemic preparedness

28. to understand this, we need to build a model… Why? –because we need evidence, structure, consistency, and simplification in order to make sound decisions… N = total population X = number of susceptible persons (as a fraction of N) Y = number of infectives µ = death rate Β = transmission rate δβ = force of infection ω = angular frequency or oscillation in susceptibility At any given moment in time, the fraction of susceptible persons in a population is dependent upon (a function of) the number of susceptible persons who die minus the number of susceptible persons who become infective. The latter fluctuates in a cyclical pattern. Duncan et al. The dynamics of measles epidemics. Theoret Pop Bio 1997;52:155-163 Bogota workshop on health services pandemic preparedness

29. pandemic spread potential k.β.D= 1 transmission efficiency rate of infective contact duration of infectivity R 0 = R 0 = basic reproductive rate of an epidemic Bogota workshop on health services pandemic preparedness

30. pandemic influenza: propagation dynamics duration of infectivity (D, days) 2 3 6 5 4 7 Bogota workshop on health services pandemic preparedness

31. so, let’s build a simple model… influenza pandemic propagation: assume a basic reproductive rate (R o ) = 1.5 assume an average generation time (days) = 3.0 then repeat … day number of new cases cummulati ve total multiply this number times 1.5 … then place answer in cell bellow … new cases are being generated every 3 days… Bogota workshop on health services pandemic preparedness

32. pandemic spread according to our simple model… incidence cummulative incidence Bogota workshop on health services pandemic preparedness

33. epidemic propagation scenarios R 0 > 1 epidemic expansion R 0 = 1 epidemic equilibrium R 0 < 1 epidemic contraction R 0 = basic reproductive rate of an epidemic Bogota workshop on health services pandemic preparedness

34. epidemiological ‘goal’ for outbreak containment t c t c …it is imperative to quickly reduce R 0 in situ (locally) Bogota workshop on health services pandemic preparedness

35. correlation of interventions for pandemic containment personal protective equipment isolation, quarantine & social distance transmission efficiency rate of infective contact duration of infectivity antiviral prophylaxis and therapy k.β.D= 1R 0 = Bogota workshop on health services pandemic preparedness

36. pandemic influenza: potencial for containment duration of infectivity (D, days) 2 3 6 5 4 7 0 10 20 30 40 50 60 70 80 0.000.050.100.150.200.250.300.350.400.450.50 transmission efficiency (B) infective contact rate (number/week) Longini IM et al; Science 2005:309 AvT: antiviral therapy Pv: pre-vaccination AvCp: antiviral chemoprophylaxis Q&I: quarantine & isolation 2 1 0 3 R0R0 AvT 1.6 Q&I + Pv + AvCp 2.4 Pv + AvCp 2.1 t c t c Bogota workshop on health services pandemic preparedness

37. pandemic containment: evidence from modeling Longini IM et al; Science 2005:309 Bogota workshop on health services pandemic preparedness t c

38. pandemic containment: evidence from modeling GTAP: Geographically Targeted Antiviral Profilaxis Longini IM et al; Science 2005:309 Bogota workshop on health services pandemic preparedness t c

39. pandemic containment: evidence from modeling Longini IM et al; Am J Epidemiol 2004:159 Bogota workshop on health services pandemic preparedness

40. pandemic containment: evidence from modeling Longini IM et al; Am J Epidemiol 2004:159 Bogota workshop on health services pandemic preparedness

41. the most certain model… Bogota workshop on health services pandemic preparedness time (weeks) impact disease burden HS surge capacity economic & social unprepared prepared

42. as a way of conclusion… Plan, Plan, Plan… Prepare, Prepare, Prepare… Practice, Practice, Practice… What to do…?, Take “home message”…? Bogota workshop on health services pandemic preparedness