JetBlue Airways Corp started transatlantic flights between New York and London on Wednesday, planning to grab market share with low fares and drive a recovery on what is usually one of the world’s busiest and most lucrative international routes. Transatlantic travel remains partially shut as the United States is still not allowing most travelers from Britain into the country because of the coronavirus pandemic. Anyone who does enter, including U.S. citizens, must present a negative COVID-19 test. The UK only opened to fully vaccinated U.S. travelers earlier in August. But New York-based JetBlue pressed ahead with the start of its daily John F. Kennedy (JFK) Airport to Heathrow service, counting on its new Airbus A321LR jets, a longer-range variant of the A321neo, to underpin profits. Fares for JetBlue’s Mint class, which features 24 lie-flat private suites, will start at $1,979 and 999 pounds, significantly cheaper than traditional prices by rivals, …