For four weekends in July and August last year, some 200,000 protesters took to the streets and squares of France, united in opposition to President Emmanuel Macron. health card. Soon, to enter cinemas, museums, cafes, trains and other shared public spaces, people in France will have to show evidence that they have been fully vaccinated, tested negative for COVID-19 infection or recovered from an infection within of the previous four months. In Paris, protesters chanted “Freedom!” and “Macron, we don’t want your pass!” Such protests have a long history. After the British government introduced a national vaccination mandate in 1853—imposing fines on parents who did not vaccinate their children against smallpox—local opposition groups formed and protests broke out periodically. Then, as now, the strongest opponents of the injunctions argued that they infringed on personal freedom and bodily autonomy. When legal requirements for vaccination arise, opposition often follows. Public health researchers generally agree that the preferred way to achieve vaccine coverage age goals is through education, information, public participation, and well-organized infrastructure — mandates should serve as a last resort. But decades of experience with efforts to vaccinate children against communicable diseases have left researchers with differing opinions about whether and when to recommend mandatory vaccinations. Some argue that coercive measures can damage public trust, sow social division and entrench opposition to vaccination. Supporters say the orders are meant to establish new social norms, not punish people. And they increase the uptake of the vaccine. Emerging research shows that for COVID-19 this has happened: “The results are quite clear and the magnitudes are really large,” says Miquel Oliu-Barton, a mathematician at the University of Paris-Dauphine in France who conducted a study. But we haven’t seen such big results everywhere, and many researchers believe that efforts to carefully assess the long-term consequences of these policies must continue. “The issue with the mandate crisis is whether the cost is worth it,” says Jeremy Ward, a sociologist who studies vaccine acceptance at the National Institute for Health and Medical Research in Paris. Before the pandemic, Ward was wary of the orders, but came to support them health card because the pandemic changed the cost-benefit analysis. “There was an emergency. We were scared,” he says. Now, if the world is to be better prepared for future pandemics — or future waves of them — learning from this experience is essential, says Noni MacDonald, a pediatrician at Dalhousie University in Halifax, Canada, and a founding member of the Global Advisory Committee on vaccine safety at the World Health Organization (WHO). Some key questions, MacDonald says, are when is the best time to introduce commands and which type is most effective. “If you’re going to do this, in what setting is it most useful?”
Policy options
France is one of dozens of countries that may offer some courses. Most followed approaches similar to health card, which requires people to be vaccinated to access shared public spaces. Some countries, such as Ecuador, introduced measures like these as soon as vaccines were available. Other countries introduced them as the Delta wave grew in mid-2021, and some introduced them much later. Some states adjusted their pass-related restrictions as the pandemic progressed. Many governments also made vaccination a requirement for employment in health care or federal jobs—and many private sector companies followed suit. Some countries focused their efforts on children (requiring vaccination to enter school, for example) or the elderly, imposing fines on unvaccinated individuals. Among the most punitive measures, Singapore made the unvaccinated pay for healthcare related to COVID-19 infections. The most common legal interventions, variously called medical cards, green cards, vaccine passports or opportunity passports, often had a previously unseen feature: people could choose not to be vaccinated if they could prove they had recovered from an infection, thus gaining some immunity to COVID-19 or if they could give a recent negative test result. Such choices made sanitary passes less restrictive than compulsory vaccination and offered those who did not wish to be vaccinated a way to participate in community life. “It’s a good compromise in terms of social cost,” says Oliu-Barton. Many of the policies, however, failed to clearly articulate their objectives. Were they able to make shared public spaces safer? To reduce the overall transmission of the virus? Or increase vaccination rates? “These are very different goals,” says Maxwell Smith, a bioethicist at Western University in Ontario, Canada, and the lead author of the WHO’s ethics guidelines on enforcing vaccination against COVID-19. Ambiguous goals can be problematic, says Smith. Clarity about policy options enhances public trust and cooperation. And clear goals are also important in assessing whether an intervention is successful. Unfortunately, says Smith, “in general, there was no clear explanation of what the goals were.” Researchers investigating the impact of policies, therefore, must choose which metrics to examine. So far, most have taken a simple approach: did the passes increase vaccination rates? But even answering that is challenging. “It’s basically a real-world policy evaluation with very noisy data,” says Shih En Lu, an economist at Simon Fraser University in Burnaby, Canada. Studies should use counterfactual scenarios as a control to assess what would have happened if the pass had not been introduced. Dariusz Walkowiak, a physician at Poznan University of Medical Sciences in Poland, used a case-control method to study the effects of vaccine mandates in neighboring Lithuania1. The Lithuanian government implemented a bargain passport program on September 13, 2021. Poland did not. “It’s not a science experiment, but we have two countries — quite similar to each other,” Walkowiak says. After the program was introduced, Lithuania’s vaccination curve rose above Poland’s, resulting in a difference of about 12% in vaccine coverage (see “Country comparison”). The simplest explanation, Walkowiak says, is that this gain was due to passports. Source: Ref 1 In Canada, Lu and colleagues examined certificate-based policies implemented in nine provinces from July to September 2021, as the number of daily vaccines administered declined2. Lu used a technique, regularly used in finance, called differences in differences. “It took advantage of the fact that different provinces introduced the policy at different times,” he says, meaning that for each implementation, data from the other eight provinces served as counter controls. To varying degrees, the announcement of a mandate caused an increase in the number of people receiving the first vaccination in all provinces. “The average effect we estimate is a 66% increase in vaccination rate,” says Lu, although the effect ranged between 34% and 326%. Larger increases were observed when the gap between announcement and implementation was narrower and when vaccination rates before policy implementation were lower. Lu wonders if this suggests the mandates are overcoming people’s reluctance about vaccines or their complacency about COVID, which in the past has been reinforced by social norms. Overall, Lu and colleagues estimated that the certificates accounted for an additional 979,000 people, about 2.9% of the eligible Canadian population, who were vaccinated. “Just looking at the graphs of daily new vaccinations, you can see very large spikes,” he says. In Europe, Melinda Mills and Tobias Rüttenauer, sociologists at the University of Oxford, UK, analyzed the effects of health conditions on vaccine uptake in Denmark, France, Germany, Israel, Italy and Switzerland3. Oliu-Barton and colleagues also looked at vaccination rates in France, Italy and Germany4. Each used so-called synthetic controls, whereby data from similar countries without mandates were combined to create comparable hypothetical countries. Security personnel check vaccination status at a market in Lima, Peru. Credit: Ernesto Benavides/AFP/Getty Mills and Rüttenauer found that some countries showed sharp peaks in absorption, most pronounced in France and Italy. In France, they looked at the 20 days between the announcement of the policy and its implementation, as well as the following 40 days. They estimated that an additional 8.6 million doses of vaccine were administered as a result. Oliu-Barton also saw the strong effects in France and Italy. It estimated that the COVID certificates directly represented 13% of the French population and 9.7% of the Italian population vaccinated in 2021. Across all studies, smaller increases were seen in Israel and Switzerland — with the hit being greater in Switzerland when a second policy introduced greater restrictions than the first. Mills and Rüttenauer found no significant increase in overall doses when Germany and Denmark introduced their first certificates, although in Denmark, passports were introduced early, when the country was still struggling to acquire enough vaccines to meet demand. Oliu-Barton’s analysis found a 6.2% jump in German vaccinations after tickets were extended in November to cover workplaces. According to Lu’s observations in Canada, in these European countries, the more unvaccinated people there were when the policy was introduced, the greater its effect. Oliu-Barton also points out that in France and Italy, there has been clear, strong communication about the introduction of certificates, compared to…
