John F. Kennedy’s only grandson has made it clear that the resurgence of measles, one of the world’s most contagious diseases, is a family matter.
Jack Schlossberg, 33, slammed his first cousin once removed, Health Secretary Robert F. Kennedy Jr., for “this deadly outbreak” of measles that has the United States poised to lose its status as having officially eliminated the disease.
South Carolina is currently in the midst of the largest measles outbreak in the country, with 789 cases and counting—the largest since measles was declared eliminated in 2000, according to federal data. Childhood vaccination rates have steadily declined to as low as 82.5 percent in some areas in the Republican-controlled state.
“MAHA MEASLES…BOBBY GONE WILD,” Schlossberg—who is running for Congress in Manhattan, New York, in one of the country’s wealthiest districts—wrote on X.
“2026 cases breaking records — USA poised to lose elimination status. Well…At least there’s a new food pyramid,” Schlossberg added, referencing Kennedy’s recent unveiling of dietary guidelines that place red meat at the top of the food pyramid.
“Thanks @RobertFKennedyJr for this deadly outbreak,” he continued. “And for having the guts to say processed foods aren’t healthy when no one else would.”
Schlossberg also shared federal data showing measles cases skyrocketing to their highest levels in decades. The graph shows 478 cases as of Jan. 26 this year, along with 2,253 cases in 2025 overall. Before Kennedy, a vaccine skeptic with no background in science, took office, there were 283 total cases in 2024 and 63 cases in 2023.
Kennedy, a conspiracy theorist who earned millions from a nonprofit he founded that has peddled anti-vax messaging, has been heavily criticized by the medical community for weakening programs and vaccine rollouts designed to protect Americans. Just this month, Kennedy, 72, announced a major overhaul of the U.S. childhood immunization schedule, cutting the number of universally recommended vaccines from 17 to 11.
Schlossberg, the son of former Biden-appointed ambassador Caroline Kennedy, is one of the most outspoken critics of his mother’s first cousin, who has spearheaded the “Make America Healthy Again” campaign.
But he isn’t the only family member speaking out. On Nov. 22, the 62nd anniversary of the Kennedy assassination, Schlossberg’s older sister, Tatiana, criticized RFK Jr. in an essay in The New Yorker. She died from a rare and rapidly progressing form of blood and bone marrow cancer on Dec. 30 at age 35.
In the essay, describing her diagnosis—caught after a routine blood test following the birth of her daughter, Josephine, in May 2024—Tatiana wrote about the fear her family experienced as RFK Jr. took a national role advancing Trump administration health policies.
“Throughout my treatment, [RFK Jr.] had been on the national stage: previously a Democrat, he was running for president as an Independent, but mostly as an embarrassment to me and the rest of my immediate family,” she wrote.
“I watched from my hospital bed as Bobby, in the face of logic and common sense, was confirmed for the position, despite never having worked in medicine, public health, or the government.”
Their mother, Caroline, also penned a letter to the Senate almost exactly a year ago in an attempt to stop his confirmation, referring to her first cousin as a “predator.”
“It’s no surprise that he keeps birds of prey as pets because he himself is a predator,” the letter reads.
The Daily Beast has reached out to Schlossberg and HHS for comment.
