LONDON—The U.S. is opening its borders to foreign air travelers just as Europe is starting to fly again, promising a fresh boost for an industry among the hardest hit by Covid-19.

Washington on Monday said it would in November start welcoming many foreigners that had been shut out of the country for more than a year. The Trump administration closed off air travel for noncitizens from places including Britain and the European Union at the start of the pandemic early last year. European leaders have called for the Biden administration...

LONDON—The U.S. is opening its borders to foreign air travelers just as Europe is starting to fly again, promising a fresh boost for an industry among the hardest hit by Covid-19.

Washington on Monday said it would in November start welcoming many foreigners that had been shut out of the country for more than a year. The Trump administration closed off air travel for noncitizens from places including Britain and the European Union at the start of the pandemic early last year. European leaders have called for the Biden administration to lift that ban.

Virgin Atlantic Airways Ltd., which relies heavily on U.S.-Europe travel, said Tuesday it had seen a 600% surge in bookings to the U.S. compared with the same time last week following the announcement, led by bookings to New York.

Deutsche Lufthansa AG reported a 40% boost in bookings, driving its shares up more than 3% early Tuesday. Shares in International Consolidated Airlines Group SA, the owner of British Airways, rose 4%.

Major travel hubs in Europe have reported passenger figures reaching the highest level since the start of the pandemic.

Photo: sarah meyssonnier/Reuters

Air travel has been recovering more strongly in Europe than the U.S. in recent months. A booming spring and summer for American airlines has started to ebb amid the spread of the Delta variant of the coronavirus across the country.

Meanwhile, some of Europe’s biggest airports have reported more than double the number of passengers traveling through the key hubs in August, versus the previous year, according to monthly traffic data published by each airport.

Major travel hubs in London, Frankfurt, Paris and Amsterdam reported passenger figures reaching the highest level since the start of the pandemic. Airline and aviation executives have cited Europe’s high vaccination rates and a vaccine passport system that has been rolling out across the European Union since June.

In the week ending Sept. 10, European airlines were operating at 103% of their capacity in early January 2020, before Covid-19 cases started affecting flights, according to Ascend by Cirium, an aviation consulting firm. In comparison, U.S. airlines flew that week at about 88% of their January 2020 capacity, retreating from highs of around 95% over the summer. U.S. airlines have reported falls in booking in recent weeks as Delta variant cases rise in many places.

In China, airlines operated at about 77% of their January 2020 capacity, rising from as little as 44% over the summer, according to the Cirium data.

The data largely reflect domestic travel and, for Europe, intra-continental flights. That is because with many international borders, including the U.S., still closed to foreigners, longer-haul international travel hasn’t yet resumed in any great measure.

Airline executives in Europe hope the U.S. decision will change that, opening trans-Atlantic routes for the likes of British Airways, Air France-KLM Group, Virgin and Lufthansa.

Meanwhile, Europe’s discounters, which specialize in the short-haul, leisure travel that has already been returning, have been flying aggressively over the summer, taking advantage of one of the first periods of consistent travel growth since the start of the crisis.

British discounter easyJet PLC said it was also starting to see a recovery in business travel.

“It’s picked up better than we thought it would,” said easyJet Chief Executive Johan Lundgren. “If you look at previous crises, there has been a lag of one to two years for business travel to come back. I don’t think that is going to be the case now.”

The recovery comes as the rollout of EU digital health certificates—vaccine and Covid testing verifications that can be stored on a passenger’s phone—becomes widespread. Lobby group Airlines for Europe estimates the EU has issued 400 million such certificates to fully vaccinated citizens across the bloc and to an additional 13 states that have signed up to the digital health system, including Switzerland and Israel. The EU’s population is about 450 million.

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Vaccination rates vary across EU countries, but some, like France, have dramatically sped up their drive over the summer.

Ryanair Holdings PLC, Europe’s biggest discounter and its biggest carrier overall by passengers, has ramped up expansion plans as it eyes opportunities across Europe. Last week, the Irish airline said it was aiming to reach an annual total of 225 million passengers in the fiscal year ending March 2026, up from pre-pandemic plans to fly 200 million customers in the same time frame.

The airline has said it is aiming to fly up to 135% of its 2019 capacity at key airports over the winter and is eyeing an aggressive expansion next summer when it is expecting demand to help lift fares. The carrier is also investing €50 million, equivalent to around $58.8 million, in a new training facility near Dublin Airport that will allow it to train over 5,000 pilots over the next five years.

Write to Benjamin Katz at ben.katz@wsj.com