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Do COVID-19 vaccine mandates still make sense?

Visitors to the National Academy of Sciences (NAS) in Washington, D.C., receive a clear reminder that, 3 years after the World Health Organization (WHO) declared COVID-19 a pandemic on 10 March 2020, it’s far from over. Before entering, they must show a guard proof that they have been vaccinated against COVID-19. Such demands were common around the world a year ago, with wide support from infectious disease scientists and public health researchers. But by now, almost everyone has had natural infections with SARS-CoV-2 or been vaccinated against the coronavirus—sometimes both—and it’s become clear that vaccine-induced immunity quickly loses its ability to prevent infection and spread of the latest variants. Some now say the mandates are outdated.

The persistent requirements are “baffling to say the least,” says Heidi Larson, an anthropologist at the London School of Hygiene & Tropical Medicine and director of the Vaccine Confidence Project. She spoke at a major infectious disease meeting this year that required all attendees to show they had had two doses of a vaccine—with no need for a recent booster. “It’s not like it’s going to mitigate the spread.”

Larson and other vaccine acceptance researchers who spoke to Science all emphasize that COVID-19 vaccines clearly prevent severe disease, but they worry maintaining the mandates could undermine future public health efforts. “Having to show these old vaccination proofs or certificates really doesn’t make sense, and it could cause harm, because people might lose trust in the competence of the organization,” says University of Konstanz psychologist Katrin Schmelz, whose research has found that institutional trust is crucial for health policy acceptance.

Mandates became common in 2021 and early 2022, after the Delta variant caused new peaks of COVID-19 hospitalizations and deaths, especially among people who had not been vaccinated. Across Europe, people had to show they were fully vaccinated before entering restaurants, shops, museums, and concert halls. The United States required federal employees to be fully vaccinated to keep their jobs. Singapore imposed a similar mandate on all employees, both public and private. And in February 2022, after months of debate, Austria passed one of the world’s first nationwide vaccine mandates, requiring the shots for all residents over age 18 and imposing fines on those who refused.

In many places, the mandates sparked large protests, but the justifications seemed compelling. COVID-19 vaccines offer powerful protection against severe disease, so the measures promised to keep hospitals from being overwhelmed. Early data also suggested the vaccines reduced overall infections and shortened the time a person was infectious. “If you can only transmit for 3 days, that’s much better than 7 days,” says Angela Branche, an infectious disease expert who studies vaccine efficacy at the University of Rochester.

Initial hopes that the vaccines would stop the spread of COVID-19 faded, however, as it became clear that protection against infection wanes after a few months. New variants that could get around vaccine-induced immunity further undermined hopes that the shots could curb spread.

In April 2022, researchers in the United Kingdom reported in The New England Journal of Medicine that, based on the health records of more than 1.5 million people, protection against symptomatic COVID-19 with the Omicron variant faded to zero 25 weeks 
after a second shot of the AstraZeneca vaccine and to just 9% 25 weeks after a second dose of the Pfizer-BioNTech vaccine. A booster dose increased protection back up above 60% for a month or two, but by 10 weeks that protection had also started to wane. (Protection against severe disease persists longer.) Now that ever-larger numbers of people have some immunity after natural infections, the real-world benefits of vaccines have become still harder to measure.

Many places and groups soon lifted their vaccine requirements or stopped enforcing them. In June, Austria revoked its law. Most European countries that required vaccine “passes” for shopping, eating out, and more dropped them by summer 2022. In October, Singapore announced it was lifting its vaccine mandate, and 1 month later the German health minister announced that even for health care workers, its vaccine requirement would be allowed to expire. Because being vaccinated was no longer a significant protection against infections with the newer variants, he said, “there’s no longer a reason,” epidemiologically, for the mandate.

Compared with Europe and Asia, the United States appears to be holding on to vaccine mandates more tightly. Many U.S. scientific groups, including NAS and AAAS (publisher of Science) still require their employees and all attendees at events and meetings to be vaccinated. Many universities continue to require vaccination or booster shots for students, staff, or both.

Although the U.S. government stopped enforcing a federal employee mandate last year in the face of lawsuits, it retains other requirements. Foreign citizens entering the country still need to show they have received a course of WHO-approved shots, a requirement that made the news last month when tennis star Novak Djokovic, who is not vaccinated, requested an exemption to compete in March tournaments in Florida. (His request was denied.)

Scientists traveling to some meetings face similar requirements. Those attending the American Astronomical Society annual gathering in January had to upload proof of vaccination, including one booster, before registering for the meeting. Larson and other attendees at the Conference on Retroviruses and Opportunistic Infections, held in February, had to show they had received two doses of a vaccine. At AAAS’s annual meeting this month, in-person attendees were also required to confirm they were vaccinated, albeit on an honor system.

None of those meetings specified the vaccination had to be recent—so attendees at some of the gatherings may have gotten their last shot more than 18 months ago. Nor did the meetings accept evidence of an infection with SARS-CoV-2, recent or otherwise, as an alternative. That doesn’t make sense to Maxwell Smith, who studies public health ethics at Western University. “If they say you need to have been vaccinated, but nothing about when those vaccines were received, nor anything about recent infection, then of course that’s less likely to achieve the objectives” of reducing transmission and infections, he says. “It would be more justifiable to say you need to have received a vaccine or been infected in the past 3 to 6 months, for example.”

Political scientist Katie Attwell, who studies vaccine policy and acceptance at the University of Western Australia, Perth, agrees. Asking for just two doses at some time in the past “feels strange and out of date,” she says. “If it was a living policy, you’d mandate the boosters.”

Branche echoes the worry that many of the lingering mandates could be counterproductive. “We don’t want people to think they’re safe from getting infected or transmitting the virus because they had the primary series 2 years ago. That’s just not true,” she says, adding that such policies might also discourage people from getting further shots.

Others say the conference vaccine requirements may be substituting for more effective ways to prevent spread of COVID-19. “If I were to see a meeting that had a vaccine requirement but then put everyone in the standard ballroom chairs shoulder to shoulder without a mask requirement, I might not consider that meeting seriously focused on COVID protection,” says University of Maryland School of Medicine epidemiologist  Meagan Fitzpatrick, who models infectious disease transmission. “The vaccine requirement does not make it OK to drop all the other efforts that one might be able to deploy.”

Many organizations are reviewing or revising their vaccine policies, especially as the end of the U.S. COVID-19 emergency declaration, set for 11 May, draws near. NAS, for example, told Science it is reassessing its current mandate. The University of Michigan, which had required all students, faculty, and staff to be vaccinated and receive a booster dose, announced in February that only students living in on-campus housing will be subject to a mandate. They will be required to have a dose of the bivalent booster, available since September 2022 and designed to protect against the original strain of SARS-CoV-2 as well as Omicron.

Rob Ernst, the university’s chief health officer, says requiring the bivalent booster means that at the start of the fall semester all residents will have had a booster that is less than 1 year old. And the rule is still needed, he argues. With as many as 1200 students living in some residence halls, “the potential for disruption is greatest in that area.” After 3 years, Ernst says, “We still have significant COVID in our community.”

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