waiver rates, herd immunity & outbreak management strategies demonstrated in a community outbreak of pertussis

Transcription

1 waiver rates, herd immunity & outbreak management strategies demonstrated in a community outbreak of pertussis Jodi Kelly MSN, BSN, RN Grand Traverse County Health Department Wendy Trute, MPH, CPHA Grand Traverse County Health Department Roger Racine, MS Michigan Department of Health and Human Services

2 objectives describe strategies for successful partnering with schools during a prolonged community outbreak identify the components of an effective communication plan with the medical community, schools, media and the public during a prolonged community outbreak estimate the balance point of approached herd immunity for Pertussis transmission in Grand Traverse County schools based on comparisons of vaccine rates by school

3 pertussis

4 pertussis

5 pertussis outbreak statistics 28,660 cases in US in in Michigan 2014 (43% increase) 91 cases in Grand Traverse County probable pertussis cases 13 Parapertussis cases average age 11.5 years age range 3 months to 44 years 24 schools, preschools, daycares

6 pertussis outbreak timeline October 21, 2014 index case Grand Traverse Academy teacher prophylaxis offered to entire close contacts classroom, family, November 4, nd wave father of child from classroom + failed to have child prophylaxed all children from family + and unvaccinated 4 different grades in same school prophylaxis for entire school of 1200 students & teachers the probables

7 pertussis outbreak timeline by November 12, confirmed cases 10 GTA & school closure home schooler 4 month old first confirmed case in TCAPs by November 19, additional confirmed cases last of the GTA cases 12 classrooms in 10 buildings by first week of december peaked

8 pertussis outbreak progression pertussis Hotline 4380 calls 4 additional phone lines & fax answering or voice mail message and yellow card prescriptions 1450 phoning or faxing supply and demand cost = barrier case investigations 1 every 2-3 months 7 per day during outbreak

9 pertussis outbreak- progression additional cases schools, daycare & preschools sports teams churches vaccination readiness adolescent health centers pharmacies physician practices GTA teacher vaccination clinic

10 pertussis- medical guidance Redbook recommends Post Exposure Prophylaxis (PEP) household members living with infants under 12 months living with immune-compromised PEP Grand Traverse Academy multiple confirmed and linked cases from 2 waves of positive tests separated by 2 week incubation period cases in other schools, PEP younger grades more likely contact hand to mouth more likely younger siblings in high risk category cautious approach to a preschool cut-off

11 pertussis- medical guidance pertussis activity non-linked confirmed cases kindergarten and younger household members living with an infant under 12 months of age living with a pregnant woman living with an immune-compromised symptomatic referred to PCP remain home from work or school for entire course of Abx re-prophylaxis parapertussis

12 outbreak operations & staffing unique challenges- key staff off medical director - 3 weeks communicable disease director - 3 weeks public information officer - 6 weeks staff shifting family planning and STD clinics reduced by 50% to maintain (1) CD nurse during the outbreak MIHP, Adolescent Clinics, Children s Special Health Care Services, Vision & Hearing, Healthy Futures, Medicaid Outreach activities extra staff (on call) assigned 2 experienced PHNs to Pertussis hotline 1-2 primary nurses assigned to investigations daily average 15 household & close contacts per confirmed case weekend/holiday/illness coverage clerical support

13 pertussis- staffing team concept all hands on deck approach: be flexible key---know your employee s strengths allow everyone to rotate and evaluate narrow team by experience and comfort daily pertussis pod management daily assignments staff scheduled vacations morning huddles to review status everyone needs to take a break

14 pertussis- strategies for successful partnering with schools know your key players: principals, school nurse, administrative assistants communicate daily with school representatives: 280 calls and s 72 school letters to parents holiday coverage be consistent & build trust find out what their needs are how can we help?

15 outbreak ah has involve emergency preparedness coordinator inform pharmacies give local physicians a heads up maintain up-to-date list of providers, pharmacies and school contacts designate outbreak work area provide team members school letters and press releases lead with kindness and calmness, trust and be honest embrace the opportunity to work together for a common goal: to stop the spread!

16 outbreak preparedness

17 outbreak operational strategies Incident Command activate? structure Using the Logic Model event / problem criteria / judgment level of activation Why implement? effective span of control at all levels effective use of resources/staff

18 outbreak operational strategies modified incident command structure essential public health services outbreak response allows for expansion additional divisions under the emergency response operations branch 1.ebola monitoring 2.pertussis 3.measles

19 outbreak operational strategies Public Health Emergency Operations Center

20 outbreak operational strategies Early & Consistent engagement of key partners: Medical Providers & Pharmacies Schools Media & Public Policy Makers / Boards

21 outbreak communication- providers

22 outbreak communication- media

23 outbreak communication- media

24 community engagement- media

25 community engagement- board Provide outbreak updates Staff recognition Request for additional staffing- 1 FTE PH nurse

26 outbreak operations- cost extra staff time comp- 88 hours overtime- 42 hours increased staff time due to outbreak management- 536 hours nursing & support staff- 660 hours prescriptions- $7000 staff time cost- $55,000 estimated cost of outbreak for GTCHD: $62,000

27 post outbreak climate schools & dr. offices changed policies! Children s House TCAPS Pediatricians

28 vaccine save lives!

29 immunization task force legislative strategies limit exemptions to medical better reporting- require school districts to expand the reporting to all grades (not kindergarten and 7th only) improving access back to school flyer on where immunizations are provided partnering with schools on waiver classes improving insurance reimbursement for all vaccines for all providers improve MCIR data entry and accessibility for all providers education & outreach physician education on approach with parents (no debate) promote best practice policies that local agencies have adopted

30 post outbreak climate proceed with caution! know before you go be prepared don t engage in debate questions, confusion & posturing from antivaccine community what % of the cases were vaccinated?

31 herd immunity..it matters no one immunized = low herd immunity some immunized = minimal herd immunity most immunized = good herd immunity

32 pertussis herd immunity pertussis vaccination threshold to prevent an outbreak R0 = basic reproduction number high threshold for pertussis 1. lower pertussis vaccines effectiveness (60-70%) 2. pertussis immunity wanes 3. transmission in children, all ages

33 pertussis outbreak spread summary initial cases were unvaccinated (RR 5.2) in a school with high waiver rates spread through entire school due to low herd immunity lack of follow-up for taking prophylaxis in many families school draws from all over community 1. lower pertussis vaccines effectiveness 2. pertussis immunity wanes 3. transmission in children 4. schools in area with high waiver rates it s complicated!... and hard to explain relative risk & why vaccinated people can get pertussis not a simple answer to how many of the cases were vaccinated?

34 epi analysis of GT Pertussis 2014

35

36 background Grand Traverse County (GTC) highest quartile of 2014 vaccination waivers outbreak: Oct 31, 2014 Jan 31, confirmed pertussis cases among GTC residents average age: 11.5 years, median of 10 years 56% female <1 yr 1-5 yrs 6-10 yrs yrs yrs 30s 40s 50s

37 timeline of onset n=77 confirmed cases by onset date Oct 12 - Oct 25 Oct 26 - Nov 8 Nov 9 - Nov 22 Nov 23 - Dec 6 Dec 7 - Dec 20 Dec 21 - Jan 3 Jan4 - Jan 17

38 affected schools elementary schools 11 of 24 schools reported pertussis cases ranging from 1 to 15 confirmed cases describing the 11 affected schools 9 traditional public schools (TCAPS) 1 private school 1 charter school middle & senior high schools 4 of 11 schools reported confirmed pertussis cases ranging from 2 to 13 cases all traditional public schools (TCAPS)

39 study proposal comparing vaccination waiver rates by school with reported Pertussis cases challenges: difficulty of assessing vaccination status by class many schools with small class sizes (reduced power) inter-school contacts within families friends and extra-curricular activities

40 methods eliminate the 8 smallest elementary schools from comparison (kindergarten classes < 25) reduce statistical noise (both case reports and waiver rates) rank order schools by vaccination waiver rates useful information in targeting vaccination goals identify any patterns of disease by vaccination rates within school communities

41 examining bias in the excluded schools included schools 13 public schools 1 charter 1 private average vaccination waiver rate: 8.8% excluded schools 4 public schools 1 charter school 3 private schools average vaccination waiver rate: 17%

42 kindergarten waiver rates and confirmed pertussis cases W_Rate Cases

43 142 if we included probable cases slam dunk analysis biased by one school we chose to remain (very) conservative only confirmed cases were included in analyses W_Rate Cases

44 comparison distribution of waiver rates within 15 elementary schools 4 schools identified with the highest waiver rates kindergarten waiver rates over 15% number of pertussis cases reported from schools 3 out of the 15 schools accounted for 81% of reported cases 2 of those 3 most affected schools were included within the four schools of highest vaccination waivers most susceptible schools

45 statistical examination relative risk compare confirmed pertussis reports from schools with kindergarten waiver rates over 15% (exposed) vs. pertussis cases reported in the schools with waiver rates less than 10% (less exposed) RR = % confidence interval: ( ) elementary students were 38% more likely to be reported as a confirmed case of pertussis in schools with kindergarten vaccination waiver rates higher than 15%

46 vaccination coverage among cases the incident school (most illnesses) reported 11 confirmed cases- only 4 had received any pertussis-containing vaccines 36% the school with the most confirmed cases (n=15) all 15 cases had received at least one pertussis containing vaccination all but two students were up to date (received 5 doses), and one had received 4 3 rd highest case count school- all 8 cases were fully vaccinated 93% 100% this is why parents of vaccinated children are worried about unvaccinated children

47 limitations collecting vaccination status & onset dates of all probable cases does not include probable cases in risk estimates could not conduct risk estimates by vaccination status over time unable to assess inter-school exposure contacts inclusion of cases from neighboring counties but which cases are related and which are independent?

48 conclusions 1. our estimates of relative risk support that higher kindergarten vaccination waivers are predictive of confirmed pertussis case reports 2. 85% to 90% may be a natural target vaccination rate for schools to support a herd immunity threshold for pertussis 3. once a community reservoir of pertussis is established, vaccination status may lose preventative effectiveness further studies are needed to determine vaccination effectiveness in communities with active pertussis reservoirs