Leaky Vaccines Support Evolution Of More-Virulent Viruses

Leaky Vaccines Support Evolution Of More-Virulent Viruses.

Scientific experiments with the herpes virus such as the one that causes Marek's disease in poultry have confirmed, for the first time, the highly controversial theory that some vaccines could allow more-virulent versions of a virus to survive.

When a vaccine works perfectly, as do the childhood vaccines for smallpox, polio, mumps, rubella, and measles, it prevents vaccinated individuals from being sickened by the disease, and it also prevents them from transmitting the virus to others, these vaccines are a type that is "perfect" because they are designed to mimic the perfect immunity that humans naturally develop after having survived one of these diseases. Research demonstrates that another vaccine type allows extremely virulent forms of a virus to survive

Vaccines that do not reduce viral replication or transmission to others — can drive the pathogens they target to evolve and become more virulent.