session 2: aligning waiting periods for vaccinate-to-live & vaccinate-to-die
DESCRIPTION
The CVOs of Australia, Canada, New Zealand and the USA initiated a scientific review to evaluate if waiting periods to regain OIE status of FMD free not practising vaccination could be 3 months irrespective of whether vaccinate-to-live or vaccinate-to-die policies were applied. The authors reviewed the following designated areas reflecting their expertise [historical review of waiting periods; Carriers; Vaccinology; DIVA technology; Post Outbreak Surveillance and Animal Products]. Current science supports eligibility to return to OIE status of FMD free country where vaccination is not practised in 3 months following an outbreak where stamping-out and emergency vaccination using higher potency vaccines are applied irrespective of whether vaccinate-to-live or vaccinate-to-die policies. This assumes aspects of vaccination affecting population immunity such as insufficient match, inadequate coverage, incorrect storage, application, maternal antibody etc are addressed. The alignment of the 3 month waiting period applies only to animal products as in 2006, the Code restricted export of live vaccinated animals from a FMD free country not practising vaccination. However, countries with OIE status, FMD free country where vaccination is practised may accept vaccinated animals and those with no OIE FMD status should not refuse them as per the OIE Code User Guide Part C a). Bilaterally negotiated additional risk mitigation measures may be needed to meet individual importing countries’ Appropriate Level of Protection (ALOP) as in any application of the Code. (c) D.Geale / EuFMD ([email protected])TRANSCRIPT
Aligning Waiting Periods
for
Vaccinate-to-live & Vaccinate-to-die
PLENARY Session II: FOCUS ON ISSUES AFFECTING FMD CONTROL IN FMD FREE REGIONS
Project Leader: Dorothy Geale (Canada) Project Team: Paul Barnett (IAH, Pirbright, United Kingdom) Grant Clarke (New Zealand) Jennifer Davis (Australia) Thomas Kasari (United States)
10/28/2012 2
Presentation Outline
Context of the QUAD FMD Project
What did the QUAD FMD Code Project conclude?
What is the rationale for this conclusion? Historical basis for 3 and 6 months
Vaccinology/Carrier/Subclinical
DIVA
Post Outbreak Surveillance
Animal Products
Conclusion/Recommendations
Next Steps
10/28/2012 3
Context In April, 2011 QUAD CVOs tasked a scientific
literature review to see if support for alignment of waiting periods for vaccinate-to-live and vaccinate-to-die strategies
Desirable Outcomes Removal of economic impediment for vaccinate-to-
live strategies
Timely decision making regarding FMD vaccination
Global reduction of mass culling of livestock through vaccination in a FMD outbreak
Core Project Team Dorothy Geale* (Canada), Tom Kasari (USA), Grant Clarke (New
Zealand), Jennifer Davis (Australia), Paul Barnett (WRL FMD)
Collaboration with IAH, Pirbright International FMD Strategic Reserves NETWORK project;
Work streams History of 3/6 mos, Vaccinology, DIVA, Post-outbreak Surveillance & Trade in animal product
10/28/2012 4
Context
Vaccinate-to-die
Vaccinate-to-live
10/28/2012 5
Presentation Outline
Context of the QUAD FMD Project
What did the QUAD FMD Code Project conclude?
What is the rationale for this conclusion?
Historical basis for 3 and 6 months
Vaccinology/Carrier/Subclinical/DIVA
Post Outbreak Surveillance
Animal Products
Conclusions/ Recommendations
Next Steps
10/28/2012 6
Conclusion
Alignment for vaccinate-to-live and vaccinate-to-die is NOT feasible for all commodities
But is feasible for vaccinated animal products using higher potency FMD vaccines
Incremental risk of vaccinated animal products can be deemed negligible with additional risk mitigation measures to meet ALOP.
Note Code Article 8.5.9.1 b) and c), deals ONLY with animal products not animals which are restricted by Article 8.5.12 3)
10/28/2012 7
Presentation Outline
Context of the QUAD FMD Project
What did the QUAD FMD Code Project conclude?
What is the rationale for this conclusion?
Historical basis for 3 and 6 months
Vaccinology/Carrier/Subclinical/DIVA
Post Outbreak Surveillance
Animal Products
Conclusions/Recommendations
Next Steps
10/28/2012 8
HISTORICAL:
No specific scientific rationale for OIE waiting periods
Years: achieve-with vacc; without vacc/recover-with vacc; without vacc
Prior to 1992: 2 yr; 3 yr /6 mos
1992-1998: 2 yr; 12 mos/12 mos; 6 mos
1998-2002: 2 yr; 12 mos/12 mos; 3 mos; 3mos
2002 to present: 2 yr; 12 mos/6 mos (DIVA); 3mos; 3mos; 6mos (DIVA).
Rationale
Relative risk determined by SCAD in 6 mos blocks for free with vacc and 3 mos for free without vacc
Vaccinate-to-live
Vaccinate-to-live
10/28/2012 9
VACCINOLOGY:
Higher potency (≥ 6PD50) vaccines protect earlier; single dose; last longer.
FMDV replication even inhibited in some animals experimentally proven relationship with potency
Infection chain is broken in 1/2 the time; less FMDV in environment exponentially = less challenge dose
No unequivocal experimental evidence that conventional vaccine which protects against disease also reduces susceptibility to infection, virus excretion or duration of persistence
Rationale
10/28/2012 10
CARRIER:
Anecdotal only; No experimental studies show cattle-cattle transmission; only SAT2 African buffalo-cattle
Undefined trigger? Strain, serotype & challenge dose differences?
Modeling with high potency parameters suggests prevalence of carrier herds is very low 0.2% with one carrier per herd
Does waiting 6 vs 3 mos make a difference? Perhaps live animals but for animal products?
Rationale
10/28/2012 11
DIVA OR NSP ASSAYS:
PANAFTOSA tests, recognized by OIE, are the foundation to FMD eradication in South America
High potency vaccines are more purified
DIVA kits available with Se (68-94%) & Sp (97-98%) but Se improved using tests in series.
DIVA validated at the herd level (appropriate for products) but lacks Se for individual animal level (already restrict live vaccinates)
Rationale
10/28/2012 12
SURVEILLANCE:
Demonstrate absence of infection impossible in a vaccinated population (demonstrate is used in Article 8.5.9.1 c); use “substantiate” for “demonstrate” as NSP assays lack Se.
Even census surveillance (EU) does not provide absolute certainty; S Korea used <1% prevalence.
South America 5% @ 95%(follow-up per Code 8.5.49)
Sentinels of limited use due to low transmission
Rationale
Need to change OIE paradigm from waiting time to statistical certainty or concept of threshold of surveillance (long term solution)
10/28/2012 13
Animal Products: [Commodity based trade]
Risk of FMDV from vaccinated products can be negligible with risk mitigation measures
Risk of mechanical contamination from carriers is negligible if correctly processed
Neutralizing antibodies are best guarantee of the absence of FMDV; No Code for milk from vaccinates
Embryos are not a risk provided handled as per IETS Manual (2007)
Rationale
10/28/2012 14
Rationale
10/28/2012 15
Presentation Outline
Context of the QUAD FMD Project
What did the QUAD FMD Code Project conclude?
What is the rationale for this conclusion?
Historical basis for 3 and 6 months
Vaccinology/Carrier/Subclinical/DIVA
Post Outbreak Surveillance
Animal Products
Conclusions/Recommendations
Next Steps
10/28/2012 16
Conclusions (repeat)
Alignment of a 3 month waiting period for vaccinate-to-live and vaccinate-to-die is feasible provided the incremental risk of vaccinated animal products is deemed negligible with additional risk mitigation.
Article 8.5.9.1 b) and c), deals ONLY with animal products as animals are restricted by Article 8.5.12 3)
Additional risk mitigation measures determined bilaterally to meet ALOP but may include bovine only (DIVA herd validated); animal identification & traceabilitiy; protection zone vaccination only; serology; no wildlife reservoir etc
10/28/2012 17
Code needs definitions for “emergency” vaccination, FMDV “circulation” versus “infection”
OIE convene ad hoc group to define statistical certainty or threshold of surveillance to demonstrate the absence of FMDV infection and FMDV circulation.
DIVA for higher potency vaccines for all species.
Promote novel vaccine such as marker VP1 gene segment with duplicate DIVA capability.
Encourage concurrent revision of EU 2003/85/EC.
,
Recommendations
Article 62 of this Directive permits derogation of the OIE waiting periods of 3 and 6 mos. provided, “…the clinical and serological survey provided for in Article 56 and the measures provided for in Article 57 have been completed and confirmed the absence of foot-and-mouth disease virus infection” (EU, 2003).
10/28/2012 18
Presentation Outline: FMD vaccinate-to- live
Context of the QUAD FMD Project
What did the QUAD FMD Code Project conclude?
What is the rationale for this conclusion?
Historical basis for 3 and 6 months
Vaccinology/Carrier/Subclinical/DIVA
Post Outbreak Surveillance
Animal Products
Conclusions/Recommendations
Next Steps
10/28/2012 19
Current Status
1. Propose alignment of waiting periods for vaccinate-to-live and vaccinate-to-die to the OIE (8.5.9 1. b) & c)
a) Concept presentation was made at July 3-5 ad hoc FMD Group under SCAD
b) Formal letter to Dr Vallat from QUAD CVOs on August 1 with revised QUAD paper with scientific evidence to support Code change
10/28/2012 20
Next Steps
c) Tabled at SCAD at end of August 2012
d) Referred back to ad hoc FMD Working Group with written rationale
e) To be reviewed in Code Commission meeting February 2013
10/28/2012 21
EU Support ?
A principle conclusion of the EU Tervuren workshops in 2007 was “Vaccination-to-live policy with subsequent freedom from infection substantiated by a survey system including NSP testing is a realistic and achievable option in FMD control.”
Next Steps
10/28/2012 22
Acknowledgements
QUAD CVOs Paul Barnett (IAH, NETWORK)- Vaccinology
Grant Clarke (New Zealand) - DIVA
Jennifer Davis (Australia) – Animal Products
Thomas Kasari (United States)- Surveillance
QUAD CVOs John Clifford (United States)-
Brian Evans/Francine Lord ( Canada)
Mark Schipp (Australia)
Matthew Stone (New Zealand)
Technical Reviewers Soren Alexandersen
Alex Donaldson
Paul Kitching
Victor Saraiva
Keith Sumption
Gavin Thomson
Questions?
QUAD EMWG Reviewers Jane Rooney/ Pam Hullinger/Randy Crom/Hernando Duque
Tom Smylie/ Jim Clark/ Al Barton/ Randy Morley
Andre van Halderen/ Katie Owen/ Brendan Pollard
Jill Mortier/ Dick Rubira