1 / 27

Disentangling / unmasking

Disentangling / unmasking. What is behind: The epidemic curve The rate. Alain Moren, Dublin, 2006. Behind the epidemic curve ?. Hepatitis A by date of onset Ogemaw county, Michigan, April - May 1968. Number of cases. 15. 50 days. one case. 30 days. 10. 5. 15 days. 0. 2. 8. 14.

damon
Download Presentation

Disentangling / unmasking

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Disentangling / unmasking • What is behind: • The epidemic curve • The rate Alain Moren, Dublin, 2006

  2. Behind the epidemic curve ?

  3. Hepatitis A by date of onsetOgemaw county, Michigan, April - May 1968 Number of cases 15 50 days one case 30 days 10 5 15 days 0 2 8 14 20 26 2 8 14 20 26 1 7 Exposure Days

  4. Gastroenteritis by day of onset Cases Common 50 source ? 40 30 Person to person ? 20 10 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Days

  5. Cases of gastroenteritis among residents of a nursing home, by date of onset, Pennsylvania, October 1986 10 One case Number of cases 5 0 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Days

  6. Cases of gastroenteritis among residents of a nursing home according to protein supplement consumption, Pa, 1986 Protein Total Cases AR% RR suppl. YES 29 22 76 3,3 NO 74 17 23 Total 103 39 38

  7. Early cases of gastroenteritis among residents of a nursing home, by date of onset, Pennsylvania, October 1986 10 Number of cases One case 5 0 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Days

  8. Early cases of gastroenteritis according to protein suppl. consumption Protein Total Early AR% RR CI 95% suppl. cases YES 29 14 48 6.9 3,2-15,8 NO 74 5 7 Total 103 19 19 Early cases = onset < 21 October

  9. Late cases of gastroenteritis among residents of a nursing home, by date of onset, Pennsylvania, October 1986 Number of cases One case 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Days

  10. Late cases of gastroenteritis according to protein suppl. consumption, Pa, 1986 Protein Total Late cases AR RR CI 95% suppl. % YES 10 3 30 2,5 0,7 - 8,9 NO 65 8 12 Total 75 11 15 Late cases = onset > 20 October

  11. Early cases of gastroenteritis lab. confirmed according to protein suppl. consumption, Pa, 1986 Protein Total Early cases AR RR CI 95% suppl. lab. + % YES 29 10 35 11,7 4,2- 38,7 NO 74 2 3 Total 103 12 12

  12. Cases of gastroenteritis by date of onset, Latuque, Quebec, 1989 70 60 50 40 30 20 10 0 7-11 8-11 9-11 10-11 11-11 12-11 13-11 14-11 15-11 16-11 17-11 18-11 19-11 20-11 Date of onset

  13. Cases of gastroenteritis by date of onset, Latuque, Quebec, 1989 70 60 50 40 30 20 10 0 7-11 8-11 9-11 10-11 11-11 12-11 13-11 14-11 15-11 16-11 17-11 18-11 19-11 20-11 Date of onset

  14. Risk factors Restaurant Hotel Shop

  15. Behind the rate ? Events Person - time denominator Denominator • Sum of individual contribution

  16. Vaccine efficacy Attack rate among vaccinated Attack rate among non vaccinated

  17. VE based on attack rates (cumulative incidence) % with disease Vaccinated Not vaccinated % with disease Epidemic duration ARNV - ARV VE = ARNV

  18. Assumptions Vaccine status as noted at begining of epidemic Vaccine status does not change during epidemic Epidemic duration is short Disease status as noted at the end of the epidemic If interested in VE by age group: ==> one individual stays in same age group during entire epidemic

  19. Incidence density rate among non vaccinated • Incidence density rate among vaccinated IDRNV - IDRV VE = IDRNV Rates expressed in person-time

  20. Measles epidemic, duration = 6 months NV V NV 6 0 V 0 6 NV V 2.5 3.5 V NV 6 0 M NV 3 0 D V 0 3 NV M V 2.5 1

  21. Time spent in each Age group Age (month) at beginning of epidemic <6 6-8 >= 9 m 6 5 1 4 2 3 3 2 3 1 1 3 2 3 3 2 4 15 0 1 2 3 4 5 6 7 8 Epidemic duration = 6 months

  22. Information needed • Date of start and end of epidemic • Date of birth • Date of death • Date of onset of measles • Incubation period (median) • Delay for protection from vaccine

More Related