A year ago, vaccines to tackle the covid pandemic still seemed like a far-off idea. Today, though, doses have been delivered to almost 40% of the world’s people—and some are being asked to prove they’re among them, leading to the rise of so-called vaccine passports. The details of these credentials vary from place to place, but at their heart they are the same: digital health records, stored on your phone, to use as proof that you are a low risk to others.

Supporters of digital vaccination credentials say the benefits are clear: they make congregating less risky while incentivizing vaccination. But critics see drawbacks and disadvantages. They say introducing restrictions infringes on civil liberties, unfairly punishes those who cannot get vaccinated (and discriminates against those who will not), unleashes another form of surveillance, and worsens inequalities rather than eradicating them. 

Faced with this divergence of views, governments are taking very different approaches. In Europe, for example, seven countries launched a “digital green certificate” at the beginning of June, with another 21 nations due to join shortly. But some places are taking the opposite stance, strictly limiting the use of such documents or even banning their development altogether.

Along with these debates, there is still basic confusion about how systems would be used. Some, like the EU’s app, are for traveling between nations. Others, like New York State’s, are for getting into everyday places like restaurants and events. The term “passport” itself is becoming more ambiguous and more politically loaded: when California governor Gavin Newsom announced the launch of his state’s digital certificate, he specifically stated, “It’s not a passport; it’s not a requirement.”

We looked at the status of digital vaccine systems in all 50 states

President Joe Biden has already said there won’t be a national app, leaving the choice to states. Some states have banned the apps outright as examples of government overreach. Often the debate over the technology seems like a proxy for a larger question: Should governments and businesses be allowed to require vaccination for covid?

A few key takeaways:

• Most states have addressed the technology in some way, either in legislation or in comments from a lawmaker, a public health official, or the governor.
• 7 states have active vaccine certification apps, rising from 4 at our last count.
• 22 states have banned the systems to some degree, typically through executive orders. Most, though not all, of these states are Republican-led. 

Each state is listed on the map according to the current legal status of vaccine apps at the time of publication. “Active” indicates that a state has created and released a digital system for showing that you have been vaccinated against covid. It does not mean that presenting vaccination credentials is mandatory state-wide, although there may be such requirements on a local level.

• Alabama: Governor Kay Ivey signed legislation on May 24 to ban digital vaccine credentials. The Alabama House of Representatives voted 76-16 to approve the bill. (Source: AP News)
• Alaska: Governor Mike Dunleavy issued Administrative Order No. 321 on April 26 stating that the state of Alaska will not require vaccine certification in order to travel to, or around, Alaska. (Source: Alaska State Website)
• Arizona: A bill passed on June 30 says employees cannot be required to get vaccinated if they have “sincerely held religious beliefs, practices or observances that prevent them from getting the covid-19 vaccine.” But exceptions can be made, and health-care institutions can require employees to be vaccinated. (Source: NASHP)
• Arkansas: On April 20, Governor Asa Hutchinson signed a law that prevents state and local governments from requiring covid-19 vaccine or proof of vaccination in order to access services. The state’s majority-Republican Senate voted 23-8 to ban digital vaccine credentials. (Source: ABC Little Rock)
• California: As of June 11, California offers a Digital Covid-19 Vaccination Record, and effective September 20, vaccine proof for 1,000+-person events will be required. (Source: NBC LA) Workers in schools and state and local governments need to be vaccinated by October 15 or take weekly tests. (Source: State Governor’s website). San Francisco now requires vaccine proof for many indoor leisure spaces, and Los Angeles could follow suit. (Source: NPR)
• Colorado: While presenting vaccine credentials is not required, residents can create a digital record of their vaccine cards on a state app. (Source: Denver Post) On July 30, Governor Jared Polis announced that unvaccinated state employees have to wear masks at work and get tested twice a week (Source: AP News), while Denver city employees and high-risk private workers will need vaccinations by September 30. (Source: AP News) 
• Connecticut: There is no vaccine certification requirement, but in March Governor Ned Lamont said that vaccine passports could be introduced in Connecticut through the private sector (Source: CT Post) An executive order signed on August 6 mandates that all employees of long-term care facilities receive at least one dose by September 7. (Source: AP News)
• Delaware: No plans to establish a digital system. Governor John Carney is considering a targeted approach that would aim vaccine mandates at high-risk groups. Verification of vaccination status remains a hurdle, the governor says. (Source: Delaware Public Media)
• Florida: Governor Ron DeSantis signed Senate Bill 2006 on April 2, effectively banning vaccine certification, blocking any business or government entity from requiring proof of covid-19 vaccination (Source: FL Governor website)
• Georgia: Governor Brian Kemp issued an executive order on May 25 prohibiting vaccine proof in state government: No vaccine passport shall be required for entry into the state of Georgia. State employers shall not have different rules for employees based on vaccination status, unless such rules are implemented using an honor code system and no proof of vaccination is required. (Source: GA Governor website)
• Hawaii: Travelers to or within Hawaii are required to upload proof of vaccination in the state’s Safe Travels program or vaccine records via several partners, including AZOVA, CLEAR, and CommonPass. State and county workers need to get vaccinated as of mid-August (Source: Hawaii News Now), while college and university students are also required to show proof of vaccination or take weekly tests. (Source: Star Advertiser)
• Idaho: Governor Brad Little issued an executive order on April 7 banning the state government from requiring or issuing vaccine digital vaccine credentials. (Source: U.S. News/AP)
• Illinois: Public health commissioner Allison Arwady said that the “Vax Pass” will be required to attend concerts and other summer events. (Source: Illinois Policy) On August 13, Chicago Public Schools announced vaccine mandates for all teachers and staff . (Source: Chicago Sun-Times)
• Indiana: HB 1405, passed on April 22, bans the state or local governments from issuing or requiring vaccine certification. (Source: WFYI Indianapolis) 
• Iowa: On May 20 Governor Kim Reynolds signed a law, House File 889, that will withhold state grants and contracts from local governments or businesses that require customers to prove they have received a covid vaccine. The law also prevents state and local governments from including a person’s vaccination status on a government-issued identification card. (Source: Des Moines Register)
• Kansas: On May 7 lawmakers approved a proposal that includes a ban on vaccine certification, which has been signed into law by Governor Laura Kelly. The law “prohibits state agencies from issuing covid-19 vaccination passports to individuals without consent, or requiring vaccination passports within the state for any purpose.” (Source: NASHP)
• Kentucky: State Representative Brandon Reed has proposed a bill that would ban the government from enforcing vaccine requirements. (Source: The Times Tribune) State workers need to get vaccinated or get tested twice a week starting October 1. (Source: Lexington Herald Leader)
• Louisiana: Vaccine certification is not required, but residents are able to show digital proof of vaccination via the LA Wallet mobile app, the state’s digital driver’s license app. (Source: AP News) A citywide vaccine mandate is slated to soon require proof of vaccination or a recent negative test for entry into restaurants, bars, and other indoor venues in New Orleans. (Source: nola.com) A statewide ban on vaccine mandates was proposed but vetoed by the governor.
• Maine: Officials are not planning on developing a statewide vaccine certification system. Residents are encouraged to use their CDC-issued immunization record card if vaccination proof is required for an activity or for travel. (Source: AP News)
• Maryland: Vaccine certification is not required currently but is not off the table. (Source: 11 News) The biotechnical distribution company MyBioSource.Com surveyed 3,000 Marylanders, and overall, 63% of Marylanders believe vaccine passports should be used. (Source: CBS Baltimore)
• Massachusetts: Governor Charlie Baker said on April 8 that he is opposed to requiring proof of vaccination, but no ban has yet been passed. (Source: Boston Globe) 
• Michigan: The state house of representatives passed a bill, HB 4667, on June 2 to ban digital vaccine certification or any other system where individuals’ civil rights are diminished by vaccine status. (Source: U.S. News) 
• Minnesota: The state senate passed bill S1589-2 in May, stating that “no person must be required to possess, wear, or display” any indicator “that the person received a negative or positive test result or possesses the antibodies for a communicable disease.” The Minnesota Department of Health has been prohibited from forcing  people to participate in covid testing, contact tracing, or digital contact tracing. (Source: Minnesota State Republican Caucus website)
• Mississippi: The state is currently not pursuing the use of a certification system. Governor Tate Reeves said in April that he doesn’t support vaccine passports. (Source: CNN) House Bill 719 was introduced to ban vaccine mandates but failed to pass in April. (Source: Mississippi Clarion Ledger)
• Missouri: In June Governor Mike Parson approved provisions to House Bill HB271, a bill that aims to ban vaccine certification systems. It prohibits local governments that receive public funds from requiring proof of vaccination for access to public transportation or other services. (Source: Springfield News Leader)
• Montana: Governor Greg Gianforte issued an executive order on April 13 prohibiting state-sponsored development and required use of vaccine proof. (Source: Montana State website) 
• Nebraska: Governor Pete Ricketts issued a statement on March 13 saying that the state will not participate in the vaccine certification program. No update on statewide ban or legislation yet. (Source: Nebraska Government website)
• Nevada: Vaccine proof is not required within the state, but there is no active statewide ban on it. Senator Jacky Rosen said on May 4 that she does not support requiring vaccine passports for local events. (Source: Las Vegas Review-Journal). Two counties, Elko and Lander, have passed resolutions to ban vaccine passports. (Source: The Nevada Independent)
• New Hampshire: Governor Chris Sununu signed the “medical freedom” immunization bill into law on July 25. The bill prohibits government agencies (including school districts) from mandating vaccines or requiring proof of vaccination for access to their buildings or services, although that may change if covid-19 vaccination is added to the state’s required immunizations list. Some exemptions apply. (Sources: AP News, New Hampshire Bulletin)
• New Jersey: Governor Phil Murphy said in April that he was open to the idea but that the state would follow federal guidance. (Source: Philadelphia Inquirer) In July, the governor unveiled a phone app called Docket, which is a place to store a digital vaccine record but “is not a vaccine passport.” (Source: nj.com)
• New Mexico: The state has no plans to issue its own certification system or limit access to services based on vaccine status, but businesses are free to make their own decisions about whom to admit and serve. (Source: New Mexico Magazine) 
• New York: The state has implemented a vaccine status system, the Excelsior Pass (Source: MIT Technology Review), which is available for iPhone and Android in nearly a dozen languages.(Source: NY State website) By September 13, New York City will require proof of covid-19 vaccination for indoor leisure activities. (Source: MIT Technology Review)
• North Carolina: The state house of representatives urged Governor Roy Cooper to reject attempts to create a vaccine proof system on April 21, with 65 Republican lawmakers sending a letter to oppose it. (Source: WCNC Charlotte) 
• North Dakota: Lawmakers passed a limited ban on vaccine certification and amended the ban into HB1465 on April 29. The law bans state and local governments from requiring proof documents and prohibits business—with some exceptions—from requiring vaccination documents of customers and patrons for access, entry, or services. The legislature also passed a resolution, SCR4016, urging Congress to refrain from passing a system for showing proof of vaccination. (Source: The Bismarck Tribune)
• Ohio: Governor Mike DeWine made a commitment that the state will not create or require vaccine certification, but he has left the issue of private-sector requirements up to individual businesses. Bill SB 111, which prohibits vaccine mandates, has passed but has not been signed into law by the governor. (Source: NASHP)
• Oklahoma: Governor Kevin Stitt issued an executive order on May 28 banning state agencies from requiring vaccinations as a condition of entry to public buildings. He also signed SB658, which prohibits schools from requiring covid vaccinations for K-12 students or implementing mask mandates that would apply only to unvaccinated students. (Source: The Oklahoman) 
• Oregon: In early August, Governor Kate Brown issued new rules requiring health-care workers to get vaccinated or submit to regular testing. (Source: AP News) The state will require all state employees to be vaccinated by October 18, including teachers and school staff. (Source: AP News) Brown also announced a strict new statewide mask mandate that even applies outdoors. (Source: AP News)
• Pennsylvania: On July 1, Governor Tom Wolf vetoed Senate Bill 618, which sought to ban vaccine certification and limit future actions during health emergencies. (Source: PA Governor)
• Rhode Island: Governor Dan McKee said on May 18 that he was leaving it to business owners and employers to decide mask-wearing and vaccination rules for themselves. (Source: The Providence Journal) But in August he announced that health-care workers at state facilities must get vaccinated before October 1 or get tested regularly. (Source: Boston Globe) City workers in Providence will face the same measures starting in October. (Source: WPRI)
• South Carolina: Governor Henry McMaster issued an executive order on May 11 that prevents local governments and schools from creating mask mandates. The order also bans local governments, state agencies, and state employees from requiring vaccine credentials. (Source: WebMD)
• South Dakota: Governor Kristi Noem issued an executive order on April 21 banning the development or use of vaccine proof systems. (Source AP News)
• Tennessee: The state senate passed a ban on vaccine passports with SB0858 on April 14; Governor Bill Lee said in April on Twitter that he “opposes vaccine passports,” adding: “The covid-19 vaccine should be a personal health choice, not a government requirement.” (Source: The Hill)
• Texas: On June 7 Governor Greg Abbot signed bill SB968, which bans businesses from requiring proof of vaccination; vaccine proofs are prohibited in the state. (Source: Texas Tribune) Local vaccine mandates are also banned via executive order. (Source: NPR) 
• Utah: A law passed in April, HB308, blocks the state government from requiring people to get vaccinated. (Source: Salt Lake Tribune) Governor Spencer Cox confirmed that vaccine certification will not be used in the state. (Source: CBS Local KUTV)
• Vermont: The state house of representatives introduced a bill, H452, to ban vaccine proof systems on May 20, but the bill did not advance. (Source: Vermont Daily Chronicle) In a recent announcement, Governor Phil Scott instituted a vaccine requirement for staff at some state facilities. Unvaccinated workers at these facilities will have to submit to regular testing. (Source: VPR)
• Virginia: Governor Ralph Northam has not ruled out proof of vaccination as a condition for entry into certain places—but in May he said his administration has no plans to use such policies in the state. (Source: Wavy.Com)
• Washington: Although a senator introduced a ban in April (which has not passed), Governor Jay Inslee announced new vaccine mandates for state and health-care workers, who will be required to show vaccine proof by October 18. (Source: AP News) Amid a spike in cases, the requirements expanded to include teachers and school staff, including those at state colleges and universities. (Source: AP News)
• West Virginia: No requirements, but Governor Jim Justice has not prohibited proof-of-vaccination requirements at any level of government. (Source: Ballotpedia)  
• Wisconsin: A series of bills were introduced in April to ban vaccine proof systems in the state. (Source: CBS Milwaukee)
• Wyoming: Governor Mark Gordon issued a directive on May 7 preventing state agencies, boards, and commissions from requiring people to show vaccination status to access state spaces or get state services. (Source: Oil City News) Representative Chuck Gray said on June 8 that he is drafting a bill to officially ban vaccine certification systems in the state. (Source: Oil City News)

What’s next

If you have information on how in your city, state, or country is using vaccine certification, or if you know of unusual uses of covid status apps, please help us keep our list up to date by emailing ctt@technologyreview.com. We will update as new information comes to light.

A previous version of this story was published on July 1, 2021. This story is part of the Pandemic Technology Project, supported by the Rockefeller Foundation.