Will Boston’s proof-of-vaccination order work without a verification system?

People will be able to show their vaccination card or a photo of it.Jessica Rinaldi/Globe Staff

In Mayor Michelle Wu’s next move to get more Bostonians vaccinated, she’s calling on local servers, bartenders, gym owners, and concert venue staff to prohibit the unvaccinated from entering their establishments.

People who want to partake in indoor dining, fitness activities, and entertainment events will need to show they’ve been inoculated as part of the city’s new proof-of-vaccination policy, called B Together, that goes into effect on Jan. 15. Some business owners see the policy as a much-needed step, especially if it encourages more people to get vaccinated.

But others have already identified holes. For example, while Brad Fredericks, owner of the downtown restaurants Fajitas & Ritas, Back Deck, and French Quarter, hopes the Boston mandate works, he said that without a verification process, the new policy is “basically the honor system.”

“My own vaccine card was issued to me without my name on it — I had to write it in,” he said. “I would be supportive of a more verifiable system, such as an app with links to vaccine history.”

Wu said the paper CDC vaccine card, or a photo of it, would count as acceptable forms of proof, as would any digital verification certificate that may be available. (Individuals who got vaccinated at CVS, Walgreens, or Walmart, for example, can obtain digital apps from those retailers.) The city is not requiring that people present other forms of identification.

About 10 states, including New York and California, are providing immunization records for the SMART Health Card system, which allows residents to get a copy of their vaccination status in the form of a verifiable QR code. The system was developed about a year ago and is based on technology from Boston Children’s Hospital.

Cities including San Francisco and New York City offer verifiable digital certificates and accept other forms of proof, too.

The SMART Health Card is not yet available in Massachusetts, but Governor Charlie Baker said in late November that a QR code-based COVID-19 vaccine certificate is coming. He also said he has no plans to implement a statewide vaccine passport that would be required to gain admission to venues.

A city spokesperson declined to comment on whether Boston would eventually implement a universal standard for its proof-of-vaccination policy, but added “we will monitor the situation and ensure the B Together policy remains rooted in equity and public health.”

Frank Nash, president of Massachusetts Independent Fitness Operators, said he doesn’t think gym employees should be asked to enforce such a mandate, since they do not have expertise to validate health records. But if they are being asked to adhere to the rule, Nash said, the government should implement a system that isn’t vulnerable to forgery or loopholes.

“If this was that dire and serious, don’t you think they would have something in place already” for verification, Nash said.

Wu on Monday announced plans to create an app to support the vaccine requirement, similar to one already used in New York City, which allows people to upload a photo of their vaccination card. The NYC app, though, does not verify the photo’s authenticity; it just helps people keep their vaccination records handy.

“My concern with those apps is just that it causes a little bit of confusion and confers some level of officialness or validity that may not be there,” said JP Pollak, cofounder of The Commons Project, a nonprofit involved with the group that designed the SMART Health Card.

He thinks verifiable credentials would make proof-of-vaccination policies such as Boston’s more effective, but acknowledged there are benefits to giving people multiple options.

There are drawbacks to digital vaccine certificates, too: They only work if businesses actually scan them. Pollak, who lives in New York, uses a separate app that the state government developed to verify vaccination, called Excelsior. But he notes that when he holds it up to enter a venue, “typically it doesn’t get scanned.”

“People don’t want to have to arm their staff with a mobile application or scanner technology,” he said. “But if we’re serious about requiring proof of vaccination for entry, that step is particularly important.”

Gus Malezis, chief executive of Imprivata, a digital identity company based in Waltham, thinks policy makers should get serious about verifiable vaccine records. Last month he went to a restaurant in Toronto — where residents have access to digital certificates — and he felt uncomfortable as wait staff inspected his CDC card.

“They were like, ‘What is this?’ ” he said. “I’m sure they were trying to validate if it was real.”

He hopes Boston’s vaccine policy looks much different in six months.

“I think it is unreasonable to expect businesses to sift through all the different types,” he said. “What if they allow me in and I presented a fake vaccination card that they didn’t catch? Are they then liable?”

Beyond the lack of a verification system, some business and health leaders have questioned the actual intent of the policy, and whether it can achieve its stated goals. Wu said the proof-of-vaccination policy is meant to “combat the winter surge, increase vaccination, and protect indoor gatherings.”

Dr. Shira Doron, an infectious disease physician and hospital epidemiologist at Tufts Medical Center, said that if the goal is to push the unvaccinated to get vaccinated, the policy might move the needle for some. But the idea that it will make indoor spaces safer, especially amid the highly transmissible Omicron variant, is a weaker argument, she said.

“I don’t disagree with this mandate, but I think that it is important to be very honest with the public, that the most effective piece is incentivizing people to get vaccinated,” Doron said. “It isn’t going to make that space perfectly safe.”

A city spokesperson said, “We are confident that the B Together policy will work to boost vaccination rates and help protect workers and members of the public.” People who may be swayed include “parents of young children, young people and others.”

Bob Luz, head of the Massachusetts Restaurant Association, said the policy could even contribute to a “false sense of security.”

“We know for a fact that these mandates have been in effect in New York City and New Orleans since September, and both of those cities have seen similar surges as of late,” he said. “So at the end of the day: What is the effect?”

Hiawatha Bray and Janelle Nanos of the Globe staff contributed to this report.