The US will soon allow entry to most foreign air travelers as long as they’re fully vaccinated against Covid-19 — while adding a testing requirement for unvaccinated Americans and barring entry for foreigners who haven’t gotten shots.

The measures, announced Monday by the White House, are the most sweeping change to US travel policies in months, and widen the gap in rules between vaccinated people — who will see measures relaxed — and the unvaccinated. The new rules will replace existing bans on foreigners’ travel to the US from certain regions, including Europe.

While the move will open the US to millions of vaccinated people, the White House cast the measure as a crackdown, pointing to stricter testing rules and a new contact tracing regime. The new policy will take effect in “early November,” according to the White House, though the precise date isn’t yet clear.

“We know vaccines are effective, including against the delta variant, and vaccines are the best line of defense against Covid, so this vaccination requirement deploys the best tool we have in our arsenal to keep people safe and prevent the spread of the virus,” White House Covid-19 response coordinator Jeff Zients told reporters on Monday.

The new rules will replace the current system, which includes outright bans on entry for foreigners who’ve been in certain regions, such as the UK and European Union, within the previous two weeks, regardless of vaccination status.

“We will protect Americans here at home and enhance the safety of international travel,” Zients said.

News of the policy change caused US airline shares to pare premarket losses. The Standard & Poor’s index of the country’s five biggest airlines rose less than 1% at 11:14 a.m. in New York, overcoming a global stock rout on anxiety over US monetary policy and China’s real estate market. American Airlines Group Inc climbed about 2%.

IAG SA, parent of trans-Atlantic specialist British Airways, gained about 11%, the most in 10 months, while Air France-KLM rose as much as 7% and Deutsche Lufthansa AG advanced 8.9%.

Before the coronavirus crisis hit, the North Atlantic corridor connecting the US and Europe was the single most profitable part of the global aviation market, filled with premium travelers paying top dollar for first- and business-class seats.

The European Union’s top industry official welcomed the policy change. “A logical decision given the success of our EU vaccination campaign,” said Industry Commissioner Thierry Breton in a tweet. He said he’d be meeting with Zients Monday “to continue fighting the pandemic.”

British Airways chief executive officer Sean Doyle called the US move an “historic moment” and said customers could now book with confidence, while his Virgin Atlantic Airways Ltd counterpart Shai Weiss said the industry had cleared a “major milestone to the reopening of travel at scale.”

“We welcome the Biden administration’s science-based approach to begin lifting the restrictions on travel to the US that were put into place at the start of the pandemic,” American Airlines CEO Doug Parker said in a statement. “We’re looking forward to welcoming more customers back to easy, seamless international trips for business, for leisure, and to reconnect with family and friends.”

Biden’s announcement comes ahead of a planned virtual vaccine summit he’ll host this Wednesday, where he will push for more global donations in a bid to head off criticism of US hoarding, and a decision to proceed with booster shots despite the World Health Organisation urging to hold off for now.

Under the new system, vaccinated travelers will still need a pre-flight Covid-19 test, within three days of departure, and will need to provide a phone number and email to begin to create a contact-tracing system that does not exist now. The vaccine requirement applies to adults, a person familiar with the plan said.

Unvaccinated American travelers will need to test within one day of departure, and will be required to test again once they arrive, Zients said.

Key details of the new system remain unclear, including what vaccines the US will recognize and whether it will insist on two doses in all cases, including for people who’ve previously been infected with the virus. It’s not clear what exemptions will be allowed.

The Centers for Disease Control and Prevention will determine the definition of fully vaccinated for international travelers, Zients said.

There’s no change to the policy along land borders, Zients said. That suggests that, as of November, vaccinated Canadians and Mexicans will be free to fly to the US, but that a ban on crossing the border by land for leisure trips will remain in place.

Throughout the pandemic, carriers on both sides of the Atlantic have lobbied forcefully for a relaxation of travel curbs that have been in place since March 2020. While Britain and the EU lifted restrictions on visiting Americans this summer, the US held off from any reciprocal loosening amid a rise in Covid-19 cases. US infections have been leveling off, though cases, hospitalizations and deaths remain high.

The policy change in Washington is coming after Britain indicated it would ease testing requirements for vaccinated arrivals, and simplify its system for regulating travel from different countries.

European countries in particular have complained that the US maintained travel restrictions on their vaccinated citizens even after they began allowing entry to vaccinated Americans.

*First appeared in BusinessTech