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Se also safety of Vaccinated food products.

* a vaccine will only give effective protection if it has been tailor-made for a particular strain as immunity is virus type-specific.

This statement assumes that vaccines are either "fully effective" or "not at all effective". In practice, the 1967 O type vaccine, produced at Merial in July, has been used and is still being used in Turkey to vaccinate against the newest strain of type 'O' The vaccine may not be a perfect match but it offers a degree of protection.
The EU now has an FMD vaccine bank with vaccines offering at least some protection against all FMD type and is regularly updated, thanks to intelligence coming in from countries around the world.
In this FMD outbreak, the vaccine of the appropriate strain ( ironically) is available just down the road.


* Current vaccines only provide 6 months protection at best

For cattle, two shots are needed when the animal has no immunity at all, as in the UK. In the past, when vaccination was allowed in Europe, cattle older than 6 months were vaccinated only once a year. This did the job.
All the same, this point is irrelevant to a successful use of emergency ring vaccination used to stop the cycle of infection in the UK.
We only need to vaccinate in response to an FMD outbreak. Therefore vaccine is needed only to the one infecting strain of virus, the one serotype. Vaccine works well, the high potency killed vaccine inducing a good immunity within 10 days of vaccination, thus preventing onward spread of the virus because there are no new susceptible animals to infect. It is unlikely the whole country would need to be covered by vaccination, but a zone round each infected premise (or in the Pirbright outbreak, round Pirbright and the 2 infected farms would be all that is required). The more infection spreads and proceeds - perhaps unremarked in the case of sheep flocks for instance - the greater the likelihood of further spread into domesitc and wild animals.


* the danger that vaccinated animals, although protected against developing the disease, may become carriers if exposed to new infections of the virus

If they run into infection with the very first days after vaccination it is possible for cattle, sheep and goats to become sub-clinically infected. (Pigs have never been found to become carriers once vaccinated) In such cases, where infection was caught in the first hours following vaccination and before it could take effect, cattle may remain sub-clinically infected "carriers" for some years. Sheep and goats for 3-9 months. The vital point is that after DECADES OF EXTENSIVE SCIENTIFIC RESEARCH, CARRIERS HAVE NEVER BEEN FOUND TO BE ABLE TO SPREAD FMD.

With any sort of vaccination, if any host is successfully vaccinated , they may boost their antibody and white cell immunity by exposure to wild type virus but they will not become "carriers" in the sense implied by the argument above. Nor will they excrete virus in to the environment. The whole basis of vaccination is to reduce virus within the environment and therefore host to host infection.


*A policy of prophylactic vaccination would also make it impossible under current EU and OIE regulations to maintain the export trade in meat and livestock.

This is the crux of the matter for big producers - the cutting off of its European and other markets. The current EU trade rules are based on the assumption above - that "Carriers are a Danger" - and this is a misconception that must be examined and put right. In any case, discriminatory tests have been developed, described by the OIE, and successfully used in practice by countries such as Uruguay to demonstrate freedom from infection.

That the legislation is still arranged to make vaccination the poor relation in disease control - and for such erroneous reasons - is surely an indication that the industry needs to lobby to change this, rather than fight vaccination itself.
Legislation must take account of the natural history and science behind infection and vaccine induced immunity . Vaccinated meat is perfectly safe. (The UK was always said 'to run its army on Brazilian and Argentinian meat'. Are we to assume that the army is fed substandard produce?)
At present in the UK, no one is arguing for the use of prophylactic vaccination, but pointing out that since emergency vaccination to live is now part of EU and UK policy the public need to be given some good reasons not to use it. No good scientific or veterinary reasons have been given.


* It is estimated* that the capitalised cost of prophylactic vaccination in the 34 years between the 1967 and 2001 outbreaks would have been £5 billion, at current prices.

It is difficult to comment on these figures. All British cattle ever might have been used for this calculation - but one would need to start with the cost of one vaccination shot and the cost of the person administering it. But the cost of not vaccinating in 2001- the cost of that outbreak still exceeds 12 BILLION EUROS. The risks of new outbreaks are increasing because of globalisation, open borders and the increased mobility of people, animals and the products.

While even the 2001 outbreak of FMD cost more than the 5 billion suggested above, the human costs and trauma involved are - as this website aims to show - beyond financial calculation


* under a policy of prophylactic vaccination, there would be periodic vaccine breakdowns, leading to eruptions of disease, with all of their associated costs. And after each breakdown, a new vaccine would need to be developed, and flocks and herds re-vaccinated.

Annual vaccination comes with an annual update of the vaccine - just like that for influenza - based on analysis of samples coming in from around the world.

Any Animal Health policy needs constant monitoring of diseases, not just on one's own country but also abroad. Bluetongue gives us a good example: It is possible that BTV-8 is endemic in Turkey but we just don't know. As for FMD however, we do have a good system of collecting data so we know, for example, that a new 'O' type has developed and is spreading in Southern Asia. (NB see also the new Bio Portal)

The arrangements that the observation addresses are not clear. Vaccine should be used as a ring outside an infected area to limit virus replication and should be used in conjunction with restriction on animal movements and, if necessary, limited culling. No one is advocating random vaccination with no other containment measures. The idea is to preserve stocks, limit infection and use all the recourses mentioned to contain disease.


* it would not be practically possible to vaccinate wildlife, a reservoir of infection would almost certainly develop in the deer population, making FMD outbreaks a constant threat.

As long as a certain minimum percentage of susceptible animals is vaccinated, the disease (if present) cannot spread. In the example of the Netherlands and many other European countries, they usually only vaccinated cattle. Sheep, pigs, goats and deer were not vaccinated (see also Uruguay in 2001) - and FMD was got rid of.
In all of South America, as a rule only cattle were vaccinated. This an important argument why "carriers" are not important. There were always sufficient susceptible sheep around in close contact with vaccinated cattle. It caused no problem.

It is possible that wild mammals are infected, the odd deer for instance. However deer are extensive and the infection probably keeps coming to a dead end; that is one infected animals does not infect another. In extensively grazing sheep the infection will peter out (as it was left to do in sheep in 1967).
This is in contrast to on-farm stock when a flock or herd is penned into a field or enclosed in a shed.


A correspondent adds:


At present in the UK, very few are arguing for the use of prophylactic vaccination - that is, wholescale vaccination throughout the country.
(See NFMG letter August 14 2007 )


And another expert adds:


Article written for Mary Critchley and Jane Barribal. Dr Ruth Watkins 11th August 2007

Arguments for why DEFRA should have vaccinated as soon as they had the information that the virus at the first farm in Normandy near Pirbright was the historic strain, O1 BFS 67.

This would have entailed a delay of 2 days while the vaccine is prepared for delivery from storage in highly concentrated form, and vaccination teams are readied.
  1. The working hypothesis must be that the virus causing this outbreak derives from Pirbright because it is a historic strain.

  2. They have the vaccine that is the perfect match for this virus originally derived from the 1967 epidemic of FMD in the UK it being the vaccine strain that 'escaped' from Pirbright.

  3. They had an area near Pirbright which would have been appropriate to identify as a vaccination zone.

  4. They could have had the "rose" of the prevailing wind for the dates that they have defined in July when the exposure of the first infected farm was deemed likely to have occurred in case of airborne spread.

  5. They should know that it would take some time to establish what had happened namely if it was a viral 'plume' of aerosolised virus, or other exposure such as a contact; the latter a point source of contamination rather than contamination spread over a wider area by a plume.

  6. They should also know that it may not be possible to demonstrate the route of escape from Pirbright. Investigation of possible sabotage or bioterrorist activity would also be very time consuming. Vaccination cannot wait upon these results.

  7. The biological characteristics of the O1 virus must be known to them, and they should have considered spread by the very many possible routes including water and wildlife such as deer- these could create a problem in control.

  8. They should be able to explain to us how the excellent killed FMD vaccine works and lay to rest the fears of the unions such as the myth of perpetuating infection by vaccination or the belief that it is necessary to cull uninfected animals just because they have been vaccinated. Also the manner in which vaccinated and infected animals are distinguished on serology testing. The science backing the policy should be clearly articulated.

  9. The legislation which they, DEFRA, are responsible for both at EU level and within the UK should not give vaccination a penalty over culling, and indeed does not anymore by the EU.

  10. The supermarkets should state publicly and categorically that vaccinated meat is safe to eat and therefore they will not label vaccinated meat as such nor make any price differential to the producer or consumer.
We may have been lucky with a point source of contamination at the first farm with waterborne spread to the second, so that the outbreak is very limited in spread. We must wait out the incubation period and also hope that infection in deer has either not occurred or that they are too dispersed to sustain infection and as hefted sheep were left in 1967 on their common pastures in extensive grazings to let any FMD infection 'burn-out'. Whilst hoping for the best, a point source, we should have taken precaution against the worst, a plume.

We are also very lucky that decades of scientific research has provided us with excellent vaccine to all the major serotypes of FMD virus. We are also fortunate that we have these scientific and vaccine establishments in the UK, and we should be ready to take advantage of the benefits they can give us.

The FMD vaccine is much better than this in that it protects against infection with wild virus of the vaccine serotype. Also if FMD infection does occur post vaccination against the same serotype such animals have never been implicated in the spread of FMD in the many decades of use of vaccination to control and eliminate FMD outbreaks worldwide. Animals infected with FMD and either never vaccinated or infected prior to vaccination have been implicated in spread through carriage and shedding of infectious virus, particularly cattle and buffalo.

With global warming we may expect the incursion of a number of exotic viruses into the domestic animals of Northern Europe, which if they are insect borne or infect a wildlife reservoir may not be eliminated. May we have diagnostics and vaccines ready to meet them. However fortunately we don't have to live with FMD and vaccination has historically been important in control and elimination of FMD infection from regions or countries. In places like Brazil or Saudi Arabia repeated incursion of FMD cannot be prevented it seems at present from poorer surrounding countries because infected animals are continually imported legally or illegally.

Why does FMD vaccine work so well?

FMD virus belongs to the family of viruses called Piconaviridae. They can be imagined as a box, the capsid, containing and protecting the delicate contents, a nucleic acid genome, an RNA molecule a mere 5000 nucleic acid bases long - as viruses they are simple and minute, much less complicated than bacteria. The function of the box or capsid is to introduce the virus into a cell whereupon it opens to release the genome so it can start to multiply. This gives rise to an infection.

After infection antibody is formed to all the virus proteins, those found in infected cells and those making up the virus itself, including the box , the capsid.

Vaccination is designed to evoke antibody to the outside surface of the box, the virus capsid.

Infection of an animal with FMD virus is distinguished from vaccination by the presence of antibodies to proteins other than those that comprise the virus, those that make up the box, the capsid. In infection antibody is made to all proteins the virus genome encodes. The virus encodes proteins that facilitate its multiplication, many new genome RNA molecules made by copying the infecting genome RNA. The RNA to RNA synthesis this process requires does not occur in any animal cell, so the infecting virus encodes the proteins necessary for this- they are not found in the FMD vaccine.

Viruses in the Picornaviridae family have well conserved neutralisation sites on the surface of their box , the capsid. The neutralisation sites are special antigenic sites that when bound by an antibody that fits perfectly or almost perfectly causes the box to remain closed and therefore the nucleic acid cannot be released even when the virus, or box, enters a cell. The nucleic acid is locked in and eventually the virus particle is harmlessly degraded by the cell. Cells cannot therefore be infected by neutralised virus.

Vaccination is designed to protect against infection by evoking antibodies against the neutralisation site.
These antibodies are present ready to meet a virus and if matched to the neutralisation site on the surface render the virus non-infectious as described above.

There are at least 7 different serotypes of FMD, that is virus types with different neutralisation sites. In order to evoke the protective neutralising antibody the vaccine used must be of the same serotype as the outbreak or epidemic virus. Hence the importance of typing an outbreak virus done most quickly now by sequencing the nucleic acid.

Each different serotype of FMD has been grown up by Merial and inactivated to form the appropriate vaccine to match each and all of the different possible serotypes of FMD. Live attenuated strains of FMD have not been developed for reasons I am not sure of, so the vaccine preparation involves the culture of very large quantities of the wild virus types, the pathogenic or disease causing virus, now historic such as the British Field Strain from the 1967 outbreak for example, before it is inactivated or 'killed' to make up the vaccine.

Though the current circulating strains of FMD, or other Picornaviridae such as polio which has 3 serotypes, do slowly evolve in that changes gradually accrue to the RNA genome the neutralisation site is as a rule highly conserved in this virus family. There must be constraints on its evolution such as any change to the neutralisation site renders the virus incompetent. This is why the laboratory strains of FMD are historic, their genome reflecting a circulating wild type virus of yester year. Historic strains of virus are used in preparation of FMD vaccines as they are in the preparation of polio vaccine.

This is in contrast to influenza virus for example where the vaccine must be updated at least annually to take account of the slow evolution of the neutralisation sites on the heamagglutinin or H molecule on the outside of the influenza virus (if a new H type comes along the vaccine must be reformulated entirely).

All virus families have different characteristics, and to some we may never be able to make protective neutralising antibody at all such as Hepatitis C virus. How lucky we are to have such a good vaccine against FMD - it is theoretically possible to eliminate FMD from the world by vaccination as has nearly been accomplished with poliovirus.


Monday, August 20 2007 ~ "I wouldn't eat vaccinated meat!"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

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