Visitors to the National Academy of Sciences (NAS) in Washington, DC, get a clear reminder that, 3 years after the World Health Organization (WHO) declared COVID-19 a pandemic on March 10, 2020, it is far from over. Before entering, they must show proof of security that they have been vaccinated against COVID-19. Such demands were common around the world a year ago, with widespread support from infectious disease scientists and public health researchers. But by now, nearly everyone has had a natural infection with SARS-CoV-2 or been vaccinated against the coronavirus — sometimes both — and it’s become clear that vaccine-induced immunity is rapidly losing its ability to prevent infection and spread of the latest variants. Some now say the mandates are obsolete.
The ongoing requirements are “baffling to say the least,” said Heidi Larson, an anthropologist at the London School of Hygiene & Tropical Medicine and director of the Vaccine Confidence Project. She was speaking at a large gathering on infectious diseases this year, where all attendees had to demonstrate they had had two doses of a vaccine — with no need for a recent booster. “It’s not like it’s going to reduce the spread.”
Larson and other vaccine acceptance researchers who spoke Science all emphasize that COVID-19 vaccines clearly prevent serious illness, but worry that enforcing the mandates could undermine future public health efforts. “It really makes no sense to show these old vaccine receipts or certificates, and it can do harm, because people could lose confidence in the competence of the organization,” says psychologist Katrin Schmelz of the University of Konstanz, whose research has shown that institutional trust is crucial to the acceptance of health policies.
Mandates became common in 2021 and early 2022, after the Delta variant drove new spikes in 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 workers 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, making the vaccinations mandatory for all residents over the age of 18 and imposing fines on those who refused.
In many places, the mandates sparked major protests, but the justifications seemed compelling. COVID-19 vaccines provide powerful protection against serious illness, so the measures promised to prevent hospitals from becoming overwhelmed. Early data also suggested that the vaccines reduced overall infections and shortened the time a person was contagious. “If you can only broadcast for 3 days, that’s much better than 7 days,” said Angela Branche, an infectious disease expert who studies vaccine efficacy at the University of Rochester.
However, initial hopes that the vaccines would stop the spread of COVID-19 faded as it became clear that protection against infection is waning after a few months. New variants that could evade vaccine-induced immunity further undermined hopes that the injections could curb the spread.
In April 2022, researchers in the United Kingdom signed up The New England Journal of Medicine that, based on the health data of over 1.5 million people, protection against symptomatic COVID-19 with the Omicron variant faded to zero 25 weeks after a second injection of the AstraZeneca vaccine and to only 9% 25 weeks after a second dose of the Pfizer-BioNTech vaccine. A booster dose increased the protection back above 60% for a month or two, but after 10 weeks that protection also started to decrease. (Protection against serious disease lasts longer.) With increasing numbers of people having some immunity after natural infections, the true benefits of vaccines are even more difficult to measure.
Many places and groups soon lifted or stopped enforcing their vaccine requirements. In June, Austria repealed its law. Most European countries that required vaccination passes for shopping, eating out and more have scrapped them by the summer of 2022. In October, Singapore announced it would lift its vaccine mandate, and a month later Germany’s health minister announced that even for healthcare workers, its vaccine requirement would be allowed to lapse. Because getting vaccinated no longer provided significant protection against infection with the newer variants, he said, “there is no longer an epidemiological reason for the mandate.”
Compared to Europe and Asia, the United States appears to be holding tighter to vaccine mandates. Many American 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 still require vaccination or booster vaccinations for students, staff, or both.
While the U.S. government stopped enforcing a federal worker’s mandate last year due to lawsuits, it maintains other requirements. Foreign citizens entering the country must still be able to prove they have received a series of WHO-approved injections, a requirement that made headlines last month when tennis star Novak Djokovic, who has not been vaccinated, applied for an exemption to participate in tournaments in March in Florida. (His request was denied.)
Scientists traveling to some meetings face similar requirements. Those attending the American Astronomical Society’s annual meeting in January were required 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 demonstrate that they had received two doses of a vaccine. At the AAAS annual meeting this month, in-person attendees also had to confirm they had been vaccinated, albeit on an honor system.
None of those meetings specified that the vaccination had to be recent – so participants in some meetings may have received their last injection more than 18 months ago. Nor did the meetings accept evidence of infection with SARS-CoV-2, recent or otherwise, as an alternative. That doesn’t make sense, according to Maxwell Smith, who studies public health ethics at Western University. “If they say you should be vaccinated, but nothing about when those vaccines were received, nor anything about recent infection, then of course it’s less likely to meet the goals” of reducing transmission and infections, he says. “It would be more justified to say, say, you must have received a vaccine or become infected in the past 3 to 6 months.”
Political scientist Katie Attwell, who studies vaccine policy and acceptance at the University of Western Australia, Perth, agrees. Asking for just two doses sometime in the past “feels strange and outdated,” she says. “If it were a living policy, you’d mandate the boosters.”
Industry reiterates concern that many of the continued mandates could be counterproductive. “We don’t want people to think they are 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 a policy could also discourage people from getting more injections.
Others say the conference’s vaccine requirements may replace more effective ways to prevent the spread of COVID-19. “If I saw a meeting that had a vaccine requirement, but then put everyone shoulder-to-shoulder in the standard ballroom seats with no mask requirement, I might not seriously consider that meeting focused on COVID protection,” says University of Maryland School of Medicine epidemiologist Meagan Fitzpatrick, who models infectious disease transmission. “The vaccination requirement does not make it okay to drop all other efforts one could make.”
Many organizations are reviewing or revising their vaccine policies, especially as the end of the US COVID-19 emergency, scheduled for May 11, approaches. For example, NAS told Science it is reviewing its current mandate. The University of Michigan, which had required all students, faculty and staff to be vaccinated and given a booster dose, announced in February that only students living in on-campus housing will be subject to a mandate. They will need a dose of the bivalent booster, available since September 2022 and designed to protect against the original strain of SARS-CoV-2 and Omicron.
Rob Ernst, the university’s chief health officer, says requiring the bivalent booster means that by 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 necessary, he argues. With as many as 1,200 students living in some residences, “the likelihood of disruption is highest in that area.” After 3 years, Ernst says, “We still have a lot of COVID in our community.”