The Science is Still Clear—Vaccines Work
The Centers for Disease Control and Prevention (CDC) recently made striking changes to its online information about the connection between vaccines and autism that put the agency on the wrong side of science.
Until now, the website said definitively that “vaccines do not cause autism.” This statement was based on decades of scientific studies that included millions of children. It is a position supported by every major medical group in the country and around the world.
The new language instead says, “The claim ‘vaccines do not cause autism’ is not an evidence-based claim because studies have not ruled out the possibility that infant vaccines cause autism.” It goes on to say that “studies supporting a link have been ignored by health authorities.” This is simply not true.
The Origin of the Myth that Vaccines Cause Autism
The myth that vaccines cause autism was created by a single study published in the Lancet in 1998. The study included just 12 children and suggested a connection between the MMR (Measles, Mumps, and Rubella) vaccine and autism. That study has since been retracted because investigations revealed deliberate fraud, including cherry-picked participants and falsified data.
In an investigation by the UK General Medical Council’s Fitness to Practise Panel, the study’s lead author, Andrew Wakefield, was found guilty of “serious professional misconduct” and lost his medical license. Further investigations revealed Wakefield’s financial motivations. Two years before the paper was published, Wakefield had been hired by a lawyer to help support a lawsuit against drug companies that manufactured MMR vaccines. Wakefield had also invested in the development of a rival measles vaccine. A series of articles in the British Medical Journal offer extensive details on this single fraudulent study and its wide-ranging impact.
Decades of Research Reveal No Link
In the decades since the Wakefield study, the possibility of a connection between vaccines and autism has been studied over-and-over again. There are now over 50 high-quality studies that together include data from over 15 million children worldwide. The research has examined multiple vaccines, ingredients used in vaccines, dosing schedules, and immune responses. All of these studies have concluded that there is no link between vaccines and autism.
Sowing doubt by saying that a link between vaccines and autism has “not been ruled out” does not reflect the way scientific research is done or should be interpreted. There is no evidence of a link.
The Impact of Vaccines on Public Health Is Undeniable
Vaccines may be the single most important public health advancement in modern times. A major study published by the Lancet in 2024 found that global immunization efforts have saved an estimated 154 lives over the past 50 years. Most of those—101 million—were infants.
Immunization efforts in the United States have been highly successful. Vaccination eradicated smallpox, a disease that had a 30% death rate. Vaccination also eradicated polio. Outbreaks of polio in the 1950s lead to over 4,000 deaths and left over 15,000 people—many of them children—paralyzed or partially paralyzed.
Vaccination had also managed to eliminate the spread of measles in the U.S. by 2000. Measles is a highly contagious disease that can be easily spread through breathing, coughing, and sneezing. Experts estimate that if one person in a room of unvaccinated people has measles, 9 out of 10 people in the room will catch it. Before the vaccine was developed in 1963, an estimated 3 to 4 million people in the U.S. were infected each year, 48,000 were hospitalized, and 400 to 500 people died.
Those numbers plummeted after vaccines were introduced. For many years, the U.S. had under 100 cases of measles each year and no deaths. As vaccination rates have gone down, however, the number of measles outbreaks has gone way up. There have been over 1,750 cases in 2025 alone, and there have been three reported deaths.
ASHA has followed the vaccine debate closely in part because of the HPV vaccine which has helped reduce the rates of cervical cancer in this country. HPV is a very contagious sexually transmitted infection (STI). HPV has been found to cause nearly all cases of cervical cancer. The vaccine protects against the types of HPV known to cause genital warts, cervical cancer, and other cancers in men and women.
Since the vaccine was introduced in 2006, rates of infection with the types of HPV it covers have dropped significantly. Infections with types that cause most HPV-related cancers and genital warts fell by 88 percent in teens and 81 percent in young women. We have the tools we need to eliminate cervical cancer—a disease that still kills over 4,000 women in this country each year—but we need widespread vaccination to do that.
The spread of misinformation about vaccines—including the disproven suggestion that they cause autism—has meant that fewer parents are vaccinating their children against preventable diseases. This will have serious results for the health of individuals and for our country as a whole.
ASHA stands by vaccines and urges parents to follow their health care providers advice on which vaccines to get and when to get them. This is the best way to keep all children safe and healthy.