France, the birthplace of vaccine pioneer Louis Pasteur, has a major problem with vaccines. Skepticism around the safety of vaccines has soared in the country, fueled by growing distrust in public health institutions and the pharmaceutical industry. French authorities hope that a new law will change that.

Last week, the French Health Ministry announced plans to make 11 vaccines mandatory for young children by 2018. French law currently mandates three vaccines — diphtheria, tetanus, and polio — for children under the age of two. The government’s proposal would expand that list to include eight other vaccines — including those against Hepatitis B, whooping cough, and measles — that were previously only recommended.

The proposal, which is to be presented to lawmakers by the end of this year, comes amid an ongoing measles outbreak across Europe, which the World Health Organization (WHO) attributed to low immunization rates. Italy passed a similar decree in May, requiring children to receive 10 vaccines as a condition for school enrollment. Germany, while stopping short of a mandate, has moved to tighten its laws on child immunization.

But some experts question whether a vaccination mandate will sway public opinion in France, where distrust in vaccines has risen alarmingly in recent years. In a survey published last year, 41 percent of respondents in France disagreed with the statement that vaccines are safe — the highest rate of distrust among the 67 countries that were surveyed, and more than three times higher than the global average.

“If it’s very top-down, [it] could totally backfire.”

“It’s one of these decisions that, if it’s well managed, could be helpful,” says Heidi Larson, director of the Vaccine Confidence Project and lead author of the survey. “If it’s very top-down, [it] could totally backfire.”

Larson says the measure will “undoubtedly” rile up hard-line anti-vaccine activists; the home of a government spokesperson was spray-painted with anti-vaccine slogans this week, and far-right politician Marine Le Pen has already voiced her opposition to the proposal. But Larson says it’s important for the government to engage with more moderate skeptics, and to convince them “that this is not just a control effort, in terms of controlling people’s actions,” but a public health initiative.

France’s vaccination rates for diphtheria and tetanus are among the highest in the world, according to the OECD, but it lags behind in measles immunization, below the 95 percent threshold considered necessary to prevent outbreaks. More than 24,000 measles cases were reported between 2008 and 2016, according to government figures, and 10 people died from the disease during that period.

Vaccination policies vary widely from country to country, though Western European nations have generally preferred voluntary approaches to mandates. States in the US require vaccines for children to attend school, though all offer medical exemptions, and some offer exemptions for religious or philosophical reasons.

France stopped mandating vaccinations in the 1950s, classifying many newly developed immunizations as “recommended,” and vaccination rates remained high through the early 2000s. But experts say high-profile legal cases over alleged vaccine side effects undermined confidence in both the government and pharmaceutical companies, while anti-vaccine activists have effectively used social media to spread conspiracy theories.

A “constellation” of anti-vaccine groups has emerged online

Conspiracy theories concerning vaccines have circulated for decades in France, but as with the “anti-vax” movement in the US, the rise of social media has allowed them to reach wider audiences. Sites such as the pro-homeopathy Sante Nature Innovation (Health Nature Innovation) and AlterInfo routinely publish articles about unfounded links between vaccines and various conditions, such as autism or sudden infant death syndrome, supported by prominent “experts” like the discredited physician Henri Joyeux. Such conspiracies appear to have resonated with the French public; fourteen of the first 16 results on an Amazon France search for “vaccines” are books that either explicitly condemn or raise doubts about vaccination.

“The difference between France and the Anglo-Saxon world is that there are very few citizen groups or associations that mobilize in favor of vaccinations,” says Jocelyn Raude, a sociologist at the EHESP French School of Public Health, who describes the call for mandatory vaccines as “courageous.” Raude says that over time, a “constellation” of anti-vaccine groups has emerged online, uniting both far-left ecologists and far-right nationalists, like Le Pen.

Recent controversies have helped fuel vaccine skepticism in France. A nationwide Hepatitis B vaccination campaign was suspended in 1998 amid concerns over possible secondary effects, and subsequent lawsuits were filed over deaths that were allegedly caused by the vaccine. Legal cases have also been filed over alleged links between the Hepatitis B vaccine and multiple sclerosis (there is no evidence of such a link), and French media outlets seized on allegations that the WHO was unduly influenced by pharmaceutical companies in launching a H1N1 flu vaccination campaign in 2009.

Conspiracies have even filtered into the French medical community, converting French doctors and fueling calls among some for more intensive vaccine education in medical schools. “At the beginning, only a few [doctors] were critical or skeptical, but now the rates are much higher,” Raude says. “Even in recent surveys we even see that a lot of them have misbeliefs about vaccinations.”

“You need people to consciously exempt, knowing fully the risks that they’re taking.”

Whether the proposed mandate will help curb such skepticism depends largely on its enforcement mechanisms, experts say. Raude says it’s unlikely that those who fail to vaccinate their children will face fines, as Italy’s law calls for, but both he and Larson agree that the law should include an exemption clause — both to appease critics, and to accommodate those who may not be able to receive vaccinations due to immune deficiencies. Such an exemption would help the government balance public health with individual liberties, Larson says, though she believes it shouldn’t be too easy to obtain.

“When they do put in these exemptions, it should be more than checking a box,” says Larson. “You need people to consciously exempt, knowing fully the risks that they’re taking.”

Experts acknowledge that an exemption risks opening the floodgates to an increasingly skeptical public, pointing to what they see as a need for greater awareness. Anne-Marie Moulin, research director at France’s National Center for Scientific Research, was part of a government committee convened last year to develop proposals to boost public confidence in vaccines. In a phone interview, she said she was in favor of expanding the mandate to include measles and whooping cough, but feared that expanding it to 11 vaccines “that people don’t know well” would be misguided without proper explanation of their importance.

The success of the proposal, in Moulin’s view, will ultimately hinge on confidence in public institutions, and she says it’s unclear whether a single piece of legislation can do much to bolster that.

“In order to reestablish confidence in vaccines, one must reestablish confidence in politics — in politicians, in the government, and in public health authorities,” Moulin says. “And for the moment, that’s a challenge, and it’s not at all certain that it will happen.”