Bartels, C.

Dulu, T.D.

Fine, P.E.M.

Knight-Jones, Theodore J.D.

Lyons, N.A.

Stärk, K.D.C.

Sumption, Keith J.

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      1 Vaccine evaluation on large-scale dairy farms using routine prophylactic schedules for FMD Nick Lyons London School of Hygiene and Tropical Medicine       2 Vaccine effectiveness: % reduction in incidence among vaccinated individuals attributable to vaccination, measured under field conditions  Reasons for poor FMD vaccine performance in the field: 1. Poor potency 2. Lack of vaccine match 3. Break in the cold chain 4. Sub-optimal coverage 5. Interference by maternally derived antibody (MDA) 6. Incorrect schedule  Background – Vaccine effectiveness       3 Kenya, Nakuru County Dairy Herd: ≈350 mainly Jersey Last known outbreaks: March 2004 (SAT2),  December 2010 (NVR) FMD Vaccination Vaccinates animals every 4 months with a locally available quadrivalent (A, O, SAT1, SAT2) vaccine Only vaccinates animals over 6 months old Aqueous-adjuvanted, Non-NSP purified vaccine. Only ≥6.0 PD50 vaccines are approved for use.     Farm A -Background       4 Serotype O  October-December 2013 Last dose 3 months before Probable source:  Farm workers Farm A - Outbreak       5 “Incidence risk” versus “Number of lifetime doses”  Farm A - Vaccine       6 “Incidence risk” versus “Number of lifetime doses”  Farm A - Vaccine Maternal antibody? Incidence plateau…       7 “Incidence risk” versus “Number of lifetime doses”  Farm A - Vaccine Maternal antibody? Incidence plateau… Declining incidence implies some vaccine effectiveness       8 40% incidence in multiply vaccinated  clearly reveals a problem…. • Potency?  • Match? • Cold chain?  Suboptimal schedules as well?   Can have multiple reasons for poor VE!  Possible reasons for incidence pattern on Farm A       9 Kenya, Nakuru County Dairy Herd: ≈650 mainly Holstein-Friesian   Last known outbreak in 2004 (unknown serotype)   FMD vaccination Vaccinates animals every 4-6 months with a locally available quadrivalent (A, O, SAT1, SAT2) vaccine Vaccinates all animals irrespective of age   Farm B - Background       10 SAT2   August – September 2012 Last vaccination 3 months before Probable source: Farm workers Farm B - Outbreak       11 “Incidence risk” versus “Number of lifetime doses” Farm B - Vaccine       12 “Incidence risk” versus “Number of lifetime doses” Farm B - Vaccine Lower incidence in youngstock…       13 “Incidence risk” versus “Number of lifetime doses” Farm B - Vaccine Incidence plateau among older animals… Lower incidence in youngstock…       14 Possible reasons for incidence pattern on Farm B Low incidence in youngstock – poorer reporting? less severe disease?, less transmission/exposure? (like Netherlands, 2001?) Vaccine match? (SAT2 VP1 sequence 13% difference to that reported by Sangula et al, 2010) Vaccine potency?  SAT2 – known to be less stable antigen requires  higher antigen dose than other serotypes Cold chain?        15 Iran, Shahriar County, Tehran Province Dairy herd: 3,500 cattle, Holstein-Friesian  Last known outbreak 4 years previously (Not Asia-1)  FMD Vaccination Every four months with trivalent (Asia-1 Shamir, O, A). Calves >2 months old get two doses one month apart as a primary course. High potency, NSP purified vaccine. Farm C - Background       16 Asia-1 January-March 2011 Last dose 11 weeks before Probable source: Local semi- nomadic sheep/goat herds  Farm C - Outbreak       17 “Incidence risk” versus “Number of lifetime doses”  Farm C - Vaccine Vaccine Matching 0.23 0.17 0.19 0.28       18 “Incidence risk” versus “Number of lifetime doses”  Farm C - Vaccine Vaccine Matching 0.23 0.17 0.19 0.28 Maternal antibody? Low incidence       19 “Incidence risk” versus “Number of lifetime doses”  Farm C - Vaccine Vaccine Matching 0.23 0.17 0.19 0.28 Maternal antibody? Most disease Another peak Low incidence       20 • Does appear to be evidence of some cumulative protection with number of doses (Farms A and C) • Cannot rule out other age related effects (although not due to exposure in these outbreaks) • Age distribution in the herd affects coverage! Vaccine protection and coverage Farm B (SAT2) Farm A (O) Farm C (Asia-1)       21 Generalisability? Field-based vaccine performance assessments provide additional information on the effectiveness of a control policy Conventional laboratory-based evaluations should be performed alongside field evaluations Standardised protocols for monitoring vaccine performance and investigating apparent low effectiveness are needed    Summary and conclusions       22 Acknowledgements Vets, Farmers and their workers at study farms Co-authors/collaborators of research: Paul Fine (LSHTM), Theo Knight-Jones (ILRI) Katharina Stӓrk (RVC), Thomas Dulu (Kenyan DVS) Chris Bartels, Keith Sumption (EuFMD), Funders:  Bloomsbury Colleges, University of London MSD Animal Health Royal Veterinary College, EuFMD  

Vaccine evaluation on large-scale dairy farms using routine prophylactic schedules for FMD

https://cgspace.cgiar.org/bitstream/10568/53929/2/Vaccine%20evaluation%20FMD.pdf

Vaccine evaluation on large-scale dairy farms using routine prophylactic schedules for FMD

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