Europe’s airlines and travel sector are bracing for a second lost summer, with rebound hopes increasingly challenged by a hobbled COVID-19 vaccine rollout, resurgent infections and new lockdowns. Airline and travel stocks fell on Friday after Paris and much of northern France shut down for a month, days after Italy introduced stiff business and movement curbs for most of the country including Rome and Milan. The setbacks hit recovery prospects for the crucial peak season, whose profits typically tide airlines through winter, when most carriers lose money even in good times. “If there’s no confidence there, demand just doesn’t come back,” said Dublin-based Alton Aviation consultant Leah Ryan, who expects the bad news on vaccines and lockdowns to hurt already weak bookings. The summer outlook also has been dented by rising infections in Greece and elsewhere, and a suspension of AstraZeneca’s vaccine by a number of European countries over health fears.