Digital vaccine passports that show a person has been vaccinated against the coronavirus are being rolled out by governments and businesses worldwide to help restart economies and allow access to events, air travel and even work, but critics warn that they could pose problems from discrimination to theft of health information and fraud.

One of the biggest concerns is that vaccine passports could be used to discriminate against those who don't have access to a vaccine or don't want it. The World Health Organization (WHO) has said that health passes tied to vaccinations will increase inequality until everyone has an opportunity to get vaccinated.

Civil liberties groups say the lack of a vaccine passport could hinder people who are ineligible for the vaccine because they have compromised immune systems, allergies or are pregnant. People who don't want to get the vaccine due to religious or cultural reasons could be blocked from some aspects of life. A digital-based app also could penalize those who don't own a smartphone.

"I foresee vaccine passports being used as a way to further disenfranchise people. For example, being used as a common restriction tactic on the marginalized, but not as stringent for the more privileged," Alexis Hancock, director of engineering for the Electronic Frontier Foundation (EFF),?a non-profit digital rights group based in San Francisco, told China Daily.

Airlines and other industry groups are calling on the Biden administration to develop coronavirus health credentials that include information about tests and vaccinations for travelers.

On Monday, Airlines for America, along with the US Chamber of Commerce, the US Travel Association and others, wrote a letter to?Jeff Zients, White House COVID-19 recovery team coordinator, asking for the administration to partner with industry on creating credentials.

The benefits of a COVID-19 health credential (CHC), according to the group, include improving the efficiency and accuracy of verifying health records, strengthening countries' risk-mitigation efforts, and preserving the privacy of passenger health data.

A CHC would include identity verification and personal health records as well as protection for personal data.?

The groups argued that the diverse and fragmented approach to digital health credentials that other countries have used for air travel-testing requirements has caused confusion and increased fraud.?

They called on the Centers for Disease Control and Prevention (CDC) to take the lead on creating a credential.?The CDC hasn't issued guidance on vaccine passports and noted that there is no international standard on vaccines or documentation of a vaccination.

"Until then, all air passengers traveling to the US, regardless of vaccination or antibody status, are required to provide a negative COVID-19 test result or documentation of recovery," said CDC spokeswoman Caitlin Shockey.

The US government hasn't decided whether it will approve vaccine passports for Americans. But President Joe Biden has issued an executive order asking multiple government agencies to "assess the feasibility" of linking coronavirus shots to international vaccination certificates and producing digital versions of them.

Biden also has said that the US will have enough coronavirus vaccine for all Americans by May, which could open up travel for millions of Americans.

Hancock also said that a digital vaccine passport with private medical data could infringe on a person's rights, especially if it will be required to be shared digitally. "Any information shared digitally is at risk of being leaked. And without good digital privacy law internationally, this information can become easily associated with the rest of a person's data without their knowledge and informed consent."

Vaccine passports can be put in a smartphone app that links a digital certificate showing a person's vaccination results. There isn't one universal app, but several firms are developing them worldwide.

In the US, IBM and Salesforce are developing a digital health pass that would show if a person has been vaccinated in order to gain access to venues such as workplaces.

If US employers want proof that an employee has been vaccinated, they can ask for it. The Equal Employment Opportunity Commission in December also said employers can require workers to get a COVID-19 vaccine and bar them from the workplace if they refuse.

A coalition of health and technology firms has launched the "Vaccination Credential Initiative'' to show proof of vaccinations. A digital pass dubbed "CommonPass" is being created by The World Economic Forum, the Commons Project, the Rockefeller Foundation and 350 public and private sector leaders from 52 countries. It is being tested by United Airlines.

Small-scale versions of vaccine passports are being tested at events and among healthcare systems countrywide.

In Los Angeles County, 'The Los Angeles Wallet Pass" was one of the first in the country to show digital proof of a coronavirus vaccine on a phone.

In New York, Governor Andrew Cuomo has launched a pilot program called the "Excelsior Pass" app, which can show an individual's vaccination or recent negative coronavirus test on a phone or it can be printed.

According to Cuomo, the pass is?intended to help major stadium venues?comply with a mandate to ensure that staff and spectators receive a negative coronavirus test within 72 hours of an event. It has been tested at Barclays Center and Madison Square Garden.

COVID-19 has led to the closure of New York's Broadway Theater District, but it could reopen soon with smaller audiences and requirements that everyone in attendance provide proof of a negative test before entry or even buying a ticket.

Despite the moves to develop some type of proof of vaccination against COVID-19, the WHO warned in January that it isn't known how effective the vaccines are against transmission, which could mean that those who get vaccinated could still pass the coronavirus on to others. And people who have already had the virus may in the future need different vaccine requirements.

"The utility of a vaccine passport is only as good as the evidence of how long the immunity lasts," David Salisbury, an associate fellow at think tank Chatham House,?told Bloomberg. "You could find yourself with a stamp in your passport that lasts longer than the antibodies in your blood."