This scares the pants off of me, the more I think about it.
Basically what happened is chickens had this disease called Marek's disease that caused tumors but wasn't usually fatal. In 1970 they invented a leaky vaccine that didn't prevent infection but only lessened symptoms. What resulted was a mutation of Marek's disease that now KILLS EVERY SINGLE CHICKEN WHO GETS IT. The vaccinated chickens are able to maintain a viral load while being healthy, that is enough to quickly kill an unvaccinated bird.
So if you own chickens, and they're going to be in contact with other chickens, you HAVE to vaccinate them or they can die easily. From a disease that was originally a nothingburger, but is now super deadly because of this leaky vaccine.
Read the related wiki entry to understand the science better:
The first Marek's disease vaccine was introduced in 1970. The disease would cause mild paralysis, with the only identifiable lesions being in neural tissue. Mortality of chickens infected with Marek's disease was quite low. Current strains of Marek virus, decades after the first vaccine was introduced, cause lymphoma formation throughout the chicken's body and mortality rates have reached 100% in unvaccinated chickens. The Marek's disease vaccine is a "leaky vaccine", which means that only the symptoms of the disease are prevented. Infection of the host and the transmission of the virus are not inhibited by the vaccine. This contrasts with most other vaccines, where infection of the host is prevented. Under normal conditions, highly virulent strains of the virus are not selected. A highly virulent strain would kill the host before the virus would have an opportunity to transmit to other potential hosts and replicate. Thus, less virulent strains are selected. These strains are virulent enough to induce symptoms but not enough to kill the host, allowing further transmission. However, the leaky vaccine changes this evolutionary pressure and permits the evolution of highly virulent strains. The vaccine's inability to prevent infection and transmission allows the spread of highly virulent strains among vaccinated chickens. The fitness of the more virulent strains is increased by the vaccine.
The evolution of Marek's disease due to vaccination has had a profound effect on the poultry industry. All chickens across the globe are now vaccinated against Marek's disease (birds hatched in private flocks for laying or exhibition are rarely vaccinated). Highly virulent strains have been selected to the point that any chicken that is unvaccinated will die if infected. Other leaky vaccines are commonly used in agriculture. One vaccine in particular is the vaccine for avian influenza. Leaky vaccine use for avian influenza can select for virulent strains.
So if we connect the dots and realize we're doing the same thing with a covid vaccine, but in humans instead of chickens.... we could very well see a scenario where you HAVE to get vaccinated or you will literally die. And then the pharma companies will go "whoopsie! our bad" as they sell billions more vaccines, even though they knew the Marek's scenario is a very real possibility. I have concerns this situation may be being created deliberately.
The possibility of this makes me so fucking mad. The pharma companies and government and media going along with it are literally creating a possible genocide and literal inescapable medical dictatorship scenario, and most don't even realize it.
People should be screaming about this from the rooftops. This is one of the most dangerous things I have seen in my lifetime, beyond even the existential threat of nuclear warfare. I hope in my heart of hearts that this is just me being a silly conspiracy theorist and reading too much in to things... but the more I read about it and understand the reality of this possibility, the more apprehensive I get. I want people to know about this and spread the word about it, because I can't believe this isn't talked about constantly. We're flirting with a massive disaster and we're completely unaware. I deeply hope I'm misunderstanding something.