On Monday, the White House announced that come November, it will lift the ban on most travelers from the European Union, China, Iran, South Africa, Brazil and India, as long as they can show proof of vaccination and a negative coronavirus test.

The new rules were widely celebrated by many countries whose citizens have been prohibited from entering the United States directly — unless they went through inconvenient, and often expensive, maneuvers.

It will, for instance, put an end to one of the odder pandemic workarounds that sprung up: Travelers from the prohibited countries spending two weeks in an intermediate country — often, Mexico or the Dominican Republic — and then obtaining a negative coronavirus test there before flying to the United States. (Travelers did not have to quarantine while visiting this other country, simply having spent 14 days before entry in a destination that wasn’t on the banned list gave them travel privileges.)

Over the past six months, Fabienne Walther, 28, from Switzerland, has helped about 20 Europeans enter the United States via Mexico. Some have rented a room in her temporary home in Playa del Carmen. In other cases, she simply offered moral support and tips about where to eat.

“The whole travel through Mexico thing is a joke,” she said, given that contracting the coronavirus is actually more of a risk in the Cancún area than in the hometowns of many of the travelers she has helped.

Soon the Mexico workaround will no longer be necessary. But the new policy, which applies to everyone traveling from abroad by air, has raised plenty of questions. Many details are yet to be worked out, but here is a look at what is known about how the new policy will affect entry into the United States.

HOW DO THE NEW RULES AFFECT PEOPLE FROM BANNED COUNTRIES?

For the past 18 months, virtually all visitors from the banned countries, including those that are members of the European Union and a handful of others, have been prohibited from traveling directly to the United States. Come early November, this policy will no longer apply, Jeffrey D. Zients, the White House pandemic coordinator, announced Monday. Individuals from these countries can fly to the United States, as they did before the pandemic, so long as they can show proof of vaccination and a negative coronavirus test taken within three days of boarding a flight. No quarantine will be required.

The CDC will also issue an order directing airlines to collect phone numbers and email addresses of travelers for a new contact-tracing system. Additional details of the contact tracing system have not yet been outlined.

Unvaccinated people who are not U.S. citizens will not be permitted to enter the United States.

ON WHAT DAY IN NOVEMBER DO THE RULES GO INTO EFFECT?

The Biden administration has not yet indicated when in November the new rules will be in place.

WHAT DOES FULLY VACCINATED MEAN? WHICH VACCINES WILL BE ACCEPTED?

A spokesperson for the Centers for Disease Control and Prevention said in a statement that the agency is still in the “regulatory process,” but said that people are considered fully vaccinated two weeks after their second dose of a Pfizer or Moderna vaccine, or two weeks after a single-dose vaccine, such as the Johnson & Johnson vaccine. Vaccines listed for emergency use by the World Health Organization, such as AstraZeneca and Oxford, will also be valid, the CDC said.

HOW DO THE NEW RULES AFFECT PEOPLE FROM COUNTRIES THAT WERE NOT ON THE BANNED LIST?

The new policy applies to everyone who is not a U.S. citizen, including individuals from Japan, Singapore, Mexico and many other countries whose citizens have been able to fly to the United States throughout the pandemic. Though vaccination status does not affect whether or not these individuals can enter the United States, in November only fully vaccinated travelers will be permitted.

Already these individuals have to show proof of a negative coronavirus test taken within three days of boarding a flight. This requirement will remain.

The policy applies to all “foreign nationals,” meaning that long-term residents of the United States who are not U.S. citizens would not be able to leave the country and then reenter unless they are fully vaccinated.

WHAT ABOUT U.S. CITIZENS?

The vaccination stipulation does not apply to U.S. citizens. But the new policy does require Americans to provide proof of a negative result from a test taken within one day of their return flight to the United States, and to test again after they land.

WHAT ABOUT CHILDREN AND OTHERS WHO CAN’T GET VACCINATED FOR MEDICAL REASONS?

Most countries that currently require vaccination for entry make exceptions for children too young to be vaccinated. It seems likely that the United States will do the same, but the White House declined to comment on specifics of this policy. It is not yet clear what other exceptions will be made.

WHAT ABOUT PEOPLE COMING FROM CANADA AND MEXICO? IF TRAVELERS GO THROUGH THE LAND BORDER, DO THEY HAVE TO BE VACCINATED?

People flying from Canada and Mexico will face the same restrictions as people flying in from other countries: They must be fully vaccinated, obtain a negative coronavirus test and provide personal information for contact tracing. Currently, the land borders with Canada and Mexico are closed for all but essential travel, a policy that is expected to remain in place until at least Oct. 21.

The new policy for international visitors only applies to people boarding an airplane, according to Zients, the White House pandemic coordinator. Therefore it’s possible that an unvaccinated person could still enter the United States by land if their reason for traveling was considered essential. The definition of “essential” offered by the U.S. Embassy and Consulates in Canada includes “work and study, critical infrastructure support, economic services and supply chains, health, immediate medical care, and safety and security.”

In Monday’s news conference, Zients declined to comment on the future of the land-border restrictions after Oct. 21, when the current policy runs out.

WHAT RESTRICTIONS ON ENTERING THE UNITED STATES WILL REMAIN COME NOVEMBER?

For people from many parts of the world — even before the pandemic — access into the United States was not easy. One of the reasons that the travel ban had such a profound effect is that it applied to many of the countries whose citizens traditionally could avoid U.S. visa requirements and had the easiest time gaining entry.

The new policy does not rewrite who can enter the United States without a visa, or rewrite the consequences for breaking visa rules by, for instance, staying in the country for longer than allowed.

But it does severely limit who can enter the United States. Only 4% of the population in Africa is fully vaccinated; fewer than a third of residents are fully vaccinated in many parts of Latin America, Asia and the Middle East. In some cases, not getting vaccinated is a choice; in others, people simply do not have access to vaccines. Regardless of their reasons, these individuals will no longer be able travel to the United States.

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