The Problem with Leaky Vaccines

While the world considers whether to give toddlers the COVID-19 vaccine, scientists are raising concerns about the potential risks that “leaky” vaccines pose to both children and adults.

A new study published in the scientific journal PLOS Biology reports that some vaccines may enable more virulent versions of a virus to survive, which puts the unvaccinated at a higher risk of severe illness.

To understand what is happening, it is necessary to look at the difference between “perfect” vaccines and “leaky” vaccines. Perfect vaccines are called this name because they mimic the natural immunity that humans develop after having certain childhood diseases like polio, smallpox, and more.

“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,” said Andrew Read, an author of the study and an Evan Pugh Professor of biology and entomology and Eberly Professor in biotechnology at Penn State University.

Studies with chickens

Professor Read was examining vaccines that could protect against malaria when he began to study Marek’s disease, which is a very contagious viral disease that infects chickens.