A concern voiced by public figures — including President-elect Donald Trump and his nominee for HHS secretary, Robert Kennedy Jr. — is that the number of vaccines administered to children may overwhelm their immune systems and contribute to conditions such as autism. This claim was denounced by medical experts, who emphasized that vaccines are designed to be safe and effective, The New York Times reported Dec. 15.
The theory that modern vaccine schedules are taxing on children's immune defenses has been widely discussed. However, experts in immunology and pediatric care say such claims are based on a misunderstanding of the immune response and current vaccine technology.
Yvonne Maldonado, MD, a pediatrician at Stanford (Calif.) University and a consultant for the CDC, told the news outlet that vaccines are cleaner, more refined and contain fewer components that trigger immune reactions compared to vaccines administered in previous decades.
Immune responses generated by vaccines are "minuscule" compared to pathogens children encounter in their daily environments, Dr. Maldonado said.
The theory that vaccines cause autism, particularly related to the measles, mumps and rubella vaccine, has been debunked by dozens of studies, according to the Times report. Claims that the MMR vaccine contains harmful substances like thimerosal, a mercury-based preservative, are also unfounded.
The CDC noted that thimerosal has not been used in most childhood vaccines since 2001 and that the form of mercury used in vaccines is not toxic at the levels present.
As vaccine safety continues to be monitored and studied, Paul Offit, MD, director of the Vaccine Education Center at Children's Hospital in Philadelphia, said current vaccines today are purer than ever thanks to advances in development and production.