Despite an uptick in anti-vaccine legislation proposed by state lawmakers in recent years, pro-vaccine bills were more likely to be enacted into law, according to a new study by researchers at Drexel University. The results were published this week in the American Journal of Public Health.

“It is reassuring to know that the legislative process is working in favor of public health. It is concerning that there are so many anti-vaccination bills introduced, but our study shows that those bills are rarely signed into law,” said study principal investigator Neal D. Goldstein, PhD, an assistant research professor in Drexel’s Dornsife School of Public Health.

The use of non-medical exemptions from vaccination requirements increased nationwide by 19 percent from 2009 to 2013, which has led to a disease resurgence in communities across the United States. However, both pro- and anti-vaccination policies vary widely state-by-state. The Drexel study, which analyzed all proposed and enacted vaccine legislation at the state level between 2011 and 2017, offers one of the first in-depth pictures of the country’s vaccination policy climate.

“If you only look at current laws, that’s history. But analyzing proposed bills gives us a flavor for what’s happening now, and perhaps for what’s to come. Are we seeing trends that may be concerning for the future?” Goldstein said.

During the seven-year study period, 175 bills related to immunization exemptions were introduced in state legislatures, with the volume increasing significantly over time. In 2011, there were 14 total bills proposed, compared to 41 in 2017.

The researchers found that the majority of vaccination legislation activity between 2011 and 2017 was consolidated to four states: New Jersey (29 total bills), New York (28), West Virginia (15) and Mississippi (12). New Jersey introduced the highest number of anti-vaccination bills (24), while New York and West Virginia introduced 14.

Of the 175 vaccination bills introduced, 92 (53 percent) were classified as anti-vaccine, and 83 (47 percent) were classified as pro-vaccine. Thirteen of the total number of bills (7 percent) were signed into law.

Although the majority of proposed legislation would have expanded access to vaccine exemptions, bills that limited exemptions — meaning they eliminated or made it more difficult for parents to opt their children out of mandatory school immunization requirements — were overwhelmingly more likely to be enacted into law. Only one anti-vaccination bill, 2011 Washington bill SB5005, ultimately became law. The law broadened the types of health care providers, beyond licensed physicians, who could sign a vaccination exemption form.

Pro-vaccine laws are an important protector for the public’s health, according to Goldstein, because such a high proportion of the population needs to be vaccinated to prevent an outbreak of contagious diseases. Measles, for example, require about 95 percent of the population to be immunized. Those who choose not to vaccinate their children for non-medical reasons are putting communities at risk, evidenced by states across the country experiencing record-high disease outbreaks this year, Goldstein said.

The recent anti-vaccination movement gained momentum after a study published in The Lancet in 1997, which suggested a link between the MMR (measles, mumps and rubella) vaccine and autism spectrum disorder. The study was subsequently debunked and retracted, and its author, Andrew Wakefield, lost his medical license.

However, that has not stopped a small, vocal minority of Americans from continuing to spread misinformation about the perceived health risks of vaccines. And Goldstein’s recent study shows that the dangerous rhetoric has found its way into state legislatures.

New Jersey Assembly Bill 497, for example, would have exempted children under six years of age from the hepatitis B vaccine requirement if the child’s mother tested negative for hepatitis B during her pregnancy. The bill explicitly linked “multiple sclerosis, chronic arthritis, autism spectrum disorder, and diabetes” as a “diseases or adverse unintended consequences associated with receipt of the hepatitis B vaccine.” There is no scientific evidence to support the bill’s claims, Goldstein said.

“Several of the bills we saw were clearly not evidenced-based,” he added. “This serves as an opportunity for pro-vaccination constituents to become involved in the legislative process and ensure that state laws reflect the state of science.”

Jonathan Purtle, DrPH, an assistant professor at Drexel’s Dornsife School of Public Health, and Joanna S. Suder, JD, deputy attorney general at the Delaware Department of Justice, co-authored this paper.