(not waiting til AH on this one)

““One way to look at that experiment is that shows vaccinating birds kills unvaccinated birds. The vaccination of one group of birds leads to the transmission of a virus so hot that it kills the other birds, said Read said……
“Our concern here, primarily and foremost, is whether this is going to happen with any of the vaccines that we give to people,”

https://www.unz.com/mwhitney/operation-vaxx-all-deplorables-codename-satans-poker/

In recent years, experts have wondered if leaky vaccines were to blame for the emergence of these hot strains. The 1970s introduction of the Marek’s disease immunizations for baby chicks kept the poultry industry from collapse, but people soon learned that vaccinated birds were catching “the bug” without subsequently dying. Then, over the last half century, symptoms for Marek’s worsened. Paralysis was more permanent; brains more quickly turned to mush….

Read’s group started their investigation by exposing vaccinated and unvaccinated Rhode Island Red chickens to one of five Marek’s disease strains that ranged from hot to cold. The hottest strains killed every unvaccinated bird within 10 days, and the team noticed that barely any virus was shed from the feathers of the chickens during that time. In contrast, vaccination extended the lifespan of birds exposed to the hottest strains, with 80 percent living longer than two months. But the vaccinated chickens were transmitting the virus, shedding 10,000 times more virus than an unvaccinated bird.

“Previously, a hot strain was so nasty, it wiped itself out. Now, you keep its host alive with a vaccine, then it can transmit and spread in the world,” Read said. “So, it’s got an evolutionary future, which it didn’t have before.”

But does this evolutionary future breed more dangerous viruses?

This study argues yes. In a second experiment, unvaccinated and vaccinated chickens were infected with one of the five Marek’s disease strains, and then put into a second arena with a second set of unimmunized birds, known as sentinels…. The virus spread to sentinel birds nine days faster if it came from a vaccinated chicken versus an unvaccinated one. In addition, sentinels died faster when exposed to vaccinated chickens versus unvaccinated chickens.

“One way to look at that experiment is that shows vaccinating birds kills unvaccinated birds. The vaccination of one group of birds leads to the transmission of a virus so hot that it kills the other birds, said Read said……

“Our concern here, primarily and foremost, is whether this is going to happen with any of the vaccines that we give to people,” said molecular biology James Bull of the University of Texas Austin, who specializes in the evolution of viruses and bacteria….

To test the imperfect vaccine hypothesis in humans, you would need monitor the vaccine response for either a large or isolated population for a long time. Doing this would allow a researcher to gauge how the vaccine interacts with the virus and if that relationship is evolving. Does the vaccine merely reduce symptoms, or does it also keep patients from getting infected and transmitting the virus?” (““This chicken vaccine makes its virus more dangerous”, PBS)