During a recent FMD outbreak (January 2016) at Indian Veterinary Research Institute, Izatnagar, in fully vaccinated (with Oil Adjuvant vaccine) Dairy farm, all calves including newborn calves were vaccinated (treated with 1 ml Raksha Ovac i/m) when the outbreak was at the maximum. The strategy is quite contrary to my beliefs and request views from learned scientists and clinicians. I believe that
1. At the time of outbreak in the affected farm vaccination should not be done.
2. In very young calves as newborn and of less than 2 months of age vaccine may not mount the immune response and may neutralize maternally transferred antibodies in calves.
3. The vaccine which failed to protect the animals eligible for vaccination after due schedule of vaccination probably may not protect young animals.
The confusion is needs to be shattered by the learned scientific society.
Technical Report Epidemiology and Statistics of Indian Veterinary Research In...
I have worked only with plant viruses. But I generally love viruses. In my opinion, your points 2,3 are correct, more over it will induce a false sense of protection which in my view is more dangerous than the virus.
I agree with you, as you have just mentioned we need to establish if those calves were from vaccinated dams that have sufficient neutralizing antibodies to the virus. Fundamentally we know that sick animals should never be vaccinated, as such implementing vaccination in a diseased herd may not produce the desired effect of vaccination. We also know that because of immature immune system in young calves their ability to mount sufficient immune response is limited so combined you have addressed the ideal. However, it will be interesting to know your findings from that reactive vaccination programme especially with the newborn calves if you have idea of the immune status of the dam at the time of vaccination.
I would second to your opinion since newborn still have their antibodies from their dam and vaccination would neutralize the remaining antibodies from their system. Furthermore the vaccination would definitely fails to mount antibody reaction in those newborn since their immune system are not fully established yet. It is also not advisable to vaccinate during outbreak and at the same time the vaccine is of attenuated in nature. There could be a reversible effects and further worsen the situation. If vaccination is still futile, I would suggest ring vaccination to be done.
Sick animals vaccination may increase risk for side effects
Vaccination in diseased herd is not in practice as no response
Immature immune system in newborn is quite discussable, but certain obligations exists
Immune status of the dam before and during delivery
Reactive vaccination programme might be considered in view of limiting the extent of large prolonged outbreaks (some diseases control)
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