Mr. Kennedy’s messages often have a grain of truth. The Children’s Health Defense website, for instance, says “vaccines contain many ingredients, some of which are known to be neurotoxic, carcinogenic and cause autoimmunity.” Vaccines do contain preservatives and additives, such as aluminum salts, which have been in use in vaccines for decades. Studies show adverse reactions are rare and typically involve skin allergies.
The Children’s Health Defense website also states that certain vaccines are not tested against placebos in clinical trials, citing polio, hepatitis and meningitis vaccines as examples. That is misleading. Brand-new vaccines — from polio to measles to Covid-19 — are tested in large clinical trials that include placebo groups. But scientists agree it would be unethical to withhold lifesaving vaccines from study participants. For that reason, when older vaccines are reformulated or updated, studies do not include a placebo group.
“Vaccine injuries can and do happen,” the website declares. That is true as well, but the federal government has an aggressive system to track and detect side effects so they can be addressed.
The measles vaccine, for instance, lowers the platelet count in about one in every 25,000 to 30,000 people. That can cause red spots from bleeding under the skin — a problem that is usually “short-lived and self-resolving,” said Dr. Paul A. Offit, the director of the Vaccine Education Center at Children’s Hospital of Philadelphia. But measles causes that problem in one in 3,000 children — roughly 10 times as many as the vaccine, he said.
“There are no risk-free choices, just choices to take different risks,” said Dr. Offit, who has been a vocal critic of Mr. Kennedy. “You could argue the greatest risk of vaccines is driving to the office to get them.”
A Movement Grows
By his own account, Mr. Kennedy was at first a reluctant critic of vaccination. He got involved in 2005, when he was an environmental lawyer suing coal-fired power plants to force them to reduce emissions of mercury and other toxic chemicals.
