Entrance to a foreign country often requires a passport.

In the age of coronavirus, entrance to schools, concerts, airlines – or anywhere else problematic for social distancing – eventually may involve a medical passport, or at least some sort of vaccination verification.

As things stand in Maine, the Center for Disease Control and Prevention is focused on continued rollout of the vaccine rather than providing people with portable proof of having been vaccinated. The Maine Immunization Program issues a card along with the initial shot, primarily as a reminder to get the second dose.

Dr. Nirav Shah, director of the Maine CDC, said progress on a uniform solution is being made at the federal Centers for Disease Control and Prevention to avoid what he called a “piecemeal approach of a hundred different apps out there that purport to be able to verify your vaccine status.”

Any solution is likely to include information about when someone received both doses, which vaccine was used and the lot number of that vaccine.

The state already asks travelers who want to avoid quarantine requirements to show proof of a recent negative COVID-19 test. Proof of vaccination is likely to be another useful tool in the effort to gradually emerge from pandemic restrictions.

“Maine continues to await federal input on how people who have been fully vaccinated can demonstrate that fact, other than with the card being used now,” said Robert Long, Maine CDC spokesman.

Long said it’s important to remember that completing the two-shot regimen does not absolve anyone’s civic duty. Safeguards remain in place.

“People who have been fully vaccinated for COVID-19 still must wear masks in public, stay 6 feet apart from others, and adhere to COVID-19 safety protocols,” he said. “Travel restrictions still apply to them.”

California’s Los Angeles County, which has more than seven times as many residents as Maine, recently partnered with a tech company called Healthvana to provide citizens with digital proof of vaccination.

Originally created to deliver test results to patients with HIV and other sexually transmitted infections, the company pivoted last year and worked with Los Angeles County – population 10 million – to provide patients with their COVID-19 test results.

After receiving their first dose from a county vaccination site, patients receive a text or email from Healthvana to view their digital vaccination record. A patient can then choose to receive a reminder for their second dose and to store their record in an Apple or Google Wallet.

Patients without smartphones can hang onto their paper vaccination card or print a PDF version of their digital record.

Susan Corbett, director of the Machias-based National Digital Equity Center, worked on an initiative to help Mainers request absentee ballots online. She said her operation could do similar training for whatever digital format ends up being accepted by the state for vaccine verification.

“With the Biden administration coming in, I think we’re going to get the money to be able to tackle this,” Corbett said. “There also may be employers who are going to require it.”

Lauren Wayne, who books shows for the State Theatre in Portland, said any use of vaccination proof for concertgoers is a long way off. There’s no telling when bands will resume touring.

“I think it’s still way too early for us here at the State to make any decisions or assumptions,” she said. “At this point, it’s all on the table.”

Pat Moody of AAA Northern New England said agents have been booking travelers to the Dominican Republic and Mexico, where no test results are necessary for entry. Caribbean islands including Anguilla, Aruba and Turks & Caicos require medical insurance as well as negative COVID-19 test results prior to arrival.

“There are some countries that are requiring a test before and a test once you arrive,” Moody said.

The International Air Transport Association is developing a vaccine passport called the IATA Travel Pass. Similarly, the World Economic Forum has reached the trials stage of its CommonPass with help from The Commons Project, a nonprofit public trust.

Many travelers are familiar with the paper-based Yellow Card, or International Certificate of Vaccination or Prophylaxis, which is widely accepted to show vaccinations and booster shots that prevent infectious diseases such as yellow fever and polio. The World Health Organization has organized a working group focused on common standards and governance for security, authentication, privacy and data exchange of a digital yellow card.

“There has been some talk of this, but I think it is a little early still,” said Steve Hewins, CEO of trade group HospitalityMaine, which represents lodging and restaurant businesses. “The real issue here likely lies with the state.”

Hewins said his group recently asked Gov. Janet Mills’ administration about any plans to relax testing requirements for out-of-state guests who have completed the two-dose vaccination regimen.

“We were told there are no changes to the state’s protocols currently planned,” he said.