Defective or ‘leaky’ vaccines may lead to even more powerful viruses, according to a study on poultry that raises concerns about vaccine development in humans.
When a vaccine works as intended — such as for smallpox, polio and measles — it protects those vaccinated and prevents the transmission of the virus.
But the study, published in PLOS Biology, reported that imperfect vaccines shielded poultry but also allowed the virus to survive in an even more pernicious form. Continue reading “Defective Vaccines May Strengthen Viruses”