On March 7, local time, a spokesperson for the US Department of Health and Human Services (HHS) announced that, given the soaring incidence of autism spectrum disorder (commonly known as "autism") among children in the United States, the US Centers for Disease Control and Prevention (CDC) plans to conduct a large-scale study to re-investigate whether there is a link between vaccines and autism. "The CDC will spare no effort in fulfilling its mission to identify the exact cause of the surge in autism cases," the spokesperson said.

As soon as this news was released, it immediately caused an uproar in public opinion. Over the past few decades, dozens of scientific studies have been carried out in different countries, including several large-scale ones involving hundreds of thousands of children. All of these studies have clearly pointed out that there is no correlation between vaccines and autism. Many researchers believe that, with the safety of vaccines having been repeatedly verified, revisiting this issue is not only a waste of extremely precious resources but may also divert attention from the "true causes" of the rising incidence of autism.

The reason why the US CDC launched this study is that its superior agency, the HHS's new secretary, Robert F. Kennedy Jr., is a well-known vaccine skeptic. Since taking office on February 13, Kennedy has vigorously promoted various anti-vaccine agendas.

In late February, Kennedy successively postponed a meeting of the CDC's Advisory Committee on Immunization Practices, halted CDC activities related to promoting influenza vaccine 接种，and then canceled a planned influenza virus strain selection meeting of the US Food and Drug Administration (FDA). This meeting was originally intended to determine the composition of the influenza vaccine strains for the 2025-2026 flu season.

Kennedy not only restarted the study on the link between vaccines and autism but also specifically hired a senior data analyst for this purpose—David Geier, a well-known anti-vaccine figure. He has spoken highly of David and has repeatedly cited the research of David and his father, Mark Geier, in public, claiming that these studies have revealed various negative impacts of vaccines. In Kennedy's book Thimerosal: Let the Science Speak, he mentions the Geier 父子 more than 200 times, praising their "contributions" in the field of autism research.