Actress Jessica Biel recently spoke out publicly against California State Bill 276, which seeks to limit medical exemptions from vaccinations.

Despite her statement that she is not "anti-vax" but is only worried about the health consequences of mandatory vaccinations, her statements have placed her on the ever-growing list of celebrities whose opinions may be contributing to a resurgence of vaccine-preventable diseases.

Biel has joined a long list of celebrities against vaccinations, including Jim Carrey, who incorrectly wrote in the Huffington Post in 2009 that vaccines have not been researched for safety; Robert F. Kennedy Jr., chairman of the Children’s Health Defense, which opposes SB 276; and Jenny McCarthy, who has been vocal for more than a decade about her belief that vaccines caused her son’s autism.

“I believe in giving doctors and the families they treat the ability to decide what’s best for their patients and the ability to provide that treatment,” Biel said in a statement on Instagram, after receiving significant backlash to her lobbying against SB.276.

Social media has amplified the voices of celebrities and has provided a platform to which increasing numbers of people turn to formulate their opinions, said Chris Altman, PharmD, manager of clinical and immunization programs for a Rite Aid in Harrisburg, Pennsylvania.

“Celebrities have a strong influence just in general,” he said. “It seems to me that they’re using those platforms to then push out their personal views on health care.”

Altman said that he thinks the strongest effects of celebrity opinion are on those who might be on the fence about vaccine, adding that if a celebrity speaks out against vaccinations, it could push that person over the edge and into the antivaccination camp.

Vaccines do not only affect the recipient, however. If the percentage of the population with vaccines continues to decrease, herd immunity, or group resistance to the spread of a disease, will fail. It is only effective if at least 90% to 95% of the population has resistance, and as that number decreases, more and more people will be infected.

Jeannette Y. Wick, MBA, RPh, FASCP, who is an assistant director of the Office of Pharmacy Professional Development at the University of Connecticut School of Pharmacy in Storrs, compares vaccinations to wearing a seatbelt,saying that though it could be considered a personal decision, for the safety of everyone on the roads we require passengers to wear them.

“I think that people think of vaccines as a personal decision, especially people who are anti-vaxxers,” she said. “And there are so many other things in society that could be a personal decision, but for the good of society we make them a legal decision: like wearing a seatbelt.”

Celebrity anti-vaxxers have a variety of concerns about adverse effects, parental freedom, and safety, but they all have something in common: None of them are scientifically accurate.

Carrey’s assertion that vaccine safety has not been researched is untrue, as scientists conduct myriad tests, including clinical trials and post-licensure studies, to ensure the safety of every vaccine on the market. Despite McCarthy’s vocal belief in vaccine-caused autism, the CDC has found absolutely no link.

The effects of vaccines are easily seen throughout the last century.

More than 25,000 Americans died from diphtheria in 1921, before the vaccine became widely used in the 1930s, according to the CDC.

Between 2004 and 2014, just 2 cases of diphtheria were reported to the CDC.

Similarly, an epidemic of rubella in 1964 to 1965 caused 11,000 miscarriages, killed 2000 infants, and infected 12.5 million Americans. Its vaccine was created in 1971, and since 2012, just 15 cases of rubella were reported to the CDC.

“At some point, medicine has to be a social decision, because we have to protect everybody,” Wick said. “Sometimes we just have to legislate things because it’s for the good of society.”