1. Vaccination as a complementary tool to control
Dr Keith Hamilton
OIE Headquarters, Paris
Comments (with copyright) / Commentaires (soumis au Copyright) :

2. OIE LITERATURE ON HPAI VACCINATION
OIE Code
Chapter : Avian Influenza
OIE Terrestrial Manual:
Chapter I.1.7: Principles of Vet. Vaccine Production
Chapter : Highly Pathogenic Avian Influenza
In Collaboration with FAO:
OIE information document on avian influenza vaccination (March 2006)
OIE guidelines on vaccination against HPAI (May 2007)
Code – trade continues if country adopts vaccination strategy SO LONG AS CAN PROVIDE RELIABLE ACCURATE INFORMATION TO SHOW DISEASE FREEDOM IN FARM OR ESTABLISHMENT FROM WHICH PRODUCT COMES
Live poultry?????
Provide guidance on surveillance
Manual – guidance on vaccine production and quality and surveillance and DIVA strategy
Also guidelines on implementation of vaccination that have been put together with help of FAO

3. GUIDELINES ON IMPLEMENTATION
To guide countries in their decisions whether to implement vaccination programs or not
Detailed guidelines and a checklist for the application, monitoring and precautionary measures in vaccination strategies
Put together with FAO – detailed guidelines with a checklist on what should be considered to decide whether it is a good idea to vaccinate or not.

4. EFFECTIVE VACCINATION
Induction of immune response
Protection against morbidity, mortality and decline of egg production
Higher resistance to infection
Decrease of virus shedding
Reduction of spread between birds and flocks
Reduce risk to human health
Vaccination should always be complemented by other measures including increased biosecurity, movement controls and stamping out
Successful vaccination relies on eliciting a good immune response. An antibody titre gives you an idea that there has been a serological response but need challenge studies to know whether vaccination is providing protection in that species. In the challenge studies need to assess viral shedding – remember this is under lab conditions.
To elicit immune response must be decent vaccine and cold chain must have been maintained.
Benefits vary between species – protection and virus shedding following vaccination and challenge
Immunised birds can still be infected but shed less virtus.
IT IS A COMPLEMENTARY MEASURE TO OTHER CLASSIC CONTROL MEASURES – biosecurity, movement controls, stamping out
Vaccination must not lead to complacency about biosecurity

5. ASSESSING WHETHER TO VACCINATE
Knowledge of the prevailing epidemiological situation
surveillance system
wild birds
disease status of neighboring countries
risk from wild birds, live bird markets, illegal trade
strain circulating
Available response systems to an outbreak
resources for other control measures
BEFORE DECIDING TO VACCINATE – should conduct an analysis and think about vaccination in context of the whole strategy. Also think about when to STOP – EXIT
I’ll run through SOME points that are worth considering – but not exhaustive – there is HELPFUL CHECKLIST in Guidance. CHECKLIST to help ensure that everything is considered that there are no gaps left i.e. come up wth a strategy and then can’t implement it due to lack of resources or decide the wrong type if vaccine
EPI- need to know exactly what is going on and if so how to target most effectively
Or is the country at high risk – do neighboring countries have it in poultry or wild birds. If wild birds is it worth vaccinating free range birds if they can’t be housed
Is there a high risk of spread within country – live bird markets etc.
If resources are not available for stamping out?? Are resources available for vaccination delivery – especially MAINTENANCE OF COLD CHAIN. COMPLETE WASTE OF TIME IF CAN’T MAINTAIN COLD CHAIN.

6. ASSESSING WHETHER TO VACCINATE
Zoo -technical aspects
Poultry production systems in place (sectors 1-4)
Poultry species reared
Biosecurity levels
Socio-economic factors
Culture, food security, religion, public acceptance, financial,
Trade aspects ZT
Lower biosecurity is higher risk i.e. free range higher risk – may vaccinate them.
Delivery to backyard flocks needs special attention, may be difficult
Spp – check vaccines is licensed. Affects dosing schedule. Spp variation
If impossible to maintain adequate biosecurity may need to vaccinate eg sector 4
SEF
Public acceptance , mass culling may not be acceptable if don’t accept culling may vaccinate (FMD)
Financial aspects – who is paying for vaccination? Does this depend on whether it is backyard or commercial?

7. IMPLEMENTATION OF VACCINATION
Vaccination Strategy
Emergency, preventive or routine
mass or targeted (inc. ring)
Choice of the vaccine strain
Homologous or Heterologous
Monovalent or Bivalent
Recombinant
Vaccine production according to OIE standards to assure high quality
Vx Strategy
Emergency – in face of EPIZOOTIC – to ‘at risk’ region
Preventative – protect high value stock, reduced risk of introduction to a new area
Routine - In entrenched or enzootic situation to reduce economic loss reduce spread (by damping down viral load) and protect livelihoods of small holders
Mass – all susceptible birds – i.e. China where it is compulsory
Targeted – define category and target it i.e. high risk or valuable
Can target resources more effectively
Includes ring vaccination – area around an outbreak
H of circulating field virus must match H of vaccine (H is the most immunogenic surface glycoprotein)
Heterologous - Different N but same H allows DIVA by serology
Mono – if know only 1 H subtype is circulating. Bivalent – if risk of H5 and H7 circulating
Recombinant – ideal for very young birds i.e. fowlpox, ND. Genetic sequence coding for HA is inserted to fowlpox or NDV

8. VACCINATION PLAN Should be part of the contingency plan
Legal framework should be in place
Vaccine distribution and cold chain
Duration of the campaign
Vaccine delivery and schedule
Monitoring
Human and financial resources
Exit strategy in all situations
Must consider how vaccine is going to get to the field and to the target birds.
THE COLD CHAIN MUST BE MAINTAINED – otherwise a waste of time and money.
How long do you expect the campaign to last – need to revaccinate birds, need to assess cost and number of vaccines needed.
Who will deliver the vaccine and what dosing schedule – depends on species.
Monitoring is essential in any vaccination campaign. Need to have lab capacity, need to calculate sample sizes etc.
When to stop vaccinating i.e. when prevalence drops below a certain level / or when deiced to switch to classic control measures

9. MONITORING
Implementation of post vaccination monitoring is highly recommended
Efficacy of vaccination
Circulation of field virus (DIVA)
Infrastructure should be available
Laboratory, personnel, financial resources etc
Because it is possible for immunized birds to be infected and shed some virus without showing signs it is very important to monitor after vaccination. Cannot rely on clinical signs in vaccinated birds.
Also need to know that vaccination is having desired effect i.e. inducing immunity to circulating field viruses. Vaccines should be matched to virus. INDONESIA initiative to match vaccines antigenically with circulating field virus.
DIVA – differentiating infected from vaccinated animals – allows detection of infected birds amongst vaccinated birds by serology if use a heterologous vaccine or by PCR
Possibility of using sentinel birds – but must be used properly… proper contact with the others, must be immunonaive and susceptible and must be identifiable
CURRENTLY NEED TO DO MORE TO MONITOR VACCINE EFFICIENCY and quality of vaccines being used
Need to think about this before vaccinating

10. PINCIPLES OF VETERINARY VACCINE PRODUCTION (Chapter I.1.7)
Quality Assurance
Efficacy and Safety tests
Stability
Batch Control
Field tests
Production facilities
Specific requirements for HPAI vaccines in chapter : highly pathogenic avian influenza
Must ensure supply of reliable, pure, safe, potent and effective vaccine.
Follow guidelines in OIE manual.

11. CONTROL IN FALCONS Effective disease surveillance and good biosecurity
Reduce risks of introduction from import/export and through capture from the wild (border inspection, health certificates, identification)
Biosecurity - falconry collections, hospitals, gatherings, feed only with birds known to be free of HPAI
Biosecurity guidance
Risks – contact with other infected birds, contaminated environment, fomites, or infected meat. risk of infection when hunting wild birds - if virus is circulating. Wild raptors have been know to be infected.
Focus on disease surveillance and biosecurity. Surveillance – clinical signs; can sometimes be difficult to detect i.e. signs such as inappetance, therefore if suspect disease – should use reliable laboratory diagnostics
Must reduce risks from legal and illegal imports. Good border inspection. Customs checks (Belgium airport incident) and health certification. Identification with microchips
Biosecurity practices at falconry events, hospitals, markets and other gatherings should any other gatherings where there is a risk of direct or indirect spread of disease.
Risk of spread by direct contact between birds, contact with contaminated environment or on fomites (cages and falconry equipment). Should have simple guidance available on biosecurity – equipment and cages for 1 birds, cleansing in between. Includes only feeding birds that is known to be free of HPAI contamination.

12. VACCINATION IN FALCONS
Limited data on vaccine efficacy in falcons
Vaccine challenge studies (inactivated H5N2) in some falcons demonstrated protection against disease and reduced viral shedding (not sterile infection)
Possibility of species variation (in protection against disease/ shedding)
Recent challenge study involving limited number of falcons demonstrated protection against disease and a reduced viral (only oropharyngeal route) shedding for falcons vaccinated with inactivated H5N2 vaccine and challenged with HPAI H5N1. Antibody levels can be an indicator of protection offered, but to get a true picture need to conduct challenge studies – also gives information about viral shedding.
Same situation for zoo birds… It is known that there is species range in response to vaccines both in terms of protection against disease and reduction in viral shedding.
Must account for national legislation on vaccination and product licensing. I don’t know of any vaccines that are licensed for use in birds of prey, so if use, it is off license – take on a risk
From initial findings there is an indication that there may be a potential role of vaccination in protecting valuable birds against disease and reducing risk of further spread. Seceral countries took this approach to valuable zoological collectionc. Less viral shedding would also reduce risks to handlers in close contact.
If vaccination is used it should be followed up with post vaccination monitoring to check against circulating virus; Vaccinated falcons that become infected are still shown to shed virus – albeit smaller quantities.
BUT prevention/control should focus on surveillance and biosecurity and vaccination should not lead to complacency about these.

13. VACCINATION IN FALCONS
National legislation and product licensing
Potential role in:
Protecting valuable birds
Reducing risks to handlers and other birds
If used, identification of vaccinated birds and good post vaccination monitoring is essential
Recent challenge study involving limited number of falcons demonstrated protection against disease and a reduced viral (only oropharyngeal route) shedding for falcons vaccinated with inactivated H5N2 vaccine and challenged with HPAI H5N1. Antibody levels can be an indicator of protection offered, but to get a true picture need to conduct challenge studies – also gives information about viral shedding.
Same situation for zoo birds… It is known that there is species range in response to vaccines both in terms of protection against disease and reduction in viral shedding.
Must account for national legislation on vaccination and product licensing. I don’t know of any vaccines that are licensed for use in birds of prey, so if use, it is off license – take on a risk
From initial findings there is an indication that there may be a potential role of vaccination in protecting valuable birds against disease and reducing risk of further spread. Seceral countries took this approach to valuable zoological collectionc. Less viral shedding would also reduce risks to handlers in close contact.
If vaccination is used it should be followed up with post vaccination monitoring to check against circulating virus; Vaccinated falcons that become infected are still shown to shed virus – albeit smaller quantities.
BUT prevention/control should focus on surveillance and biosecurity and vaccination should not lead to complacency about these.
Biosecurity and surveillance are the recommended primary control options

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