Shares of airline and cruise line operators are falling in premarket trading after the World Health Organization warned that a new Covid-19 variant has been detected in South Africa. Following the warning, the European Union temporarily banned flights travel from several countries in South Africa. Publicly traded companies in the space include Alaska Air (ALK), American Airlines (AAL), Delta Air Lines (DAL), JetBlue (JBLU), Southwest (LUV), Spirit Airlines (SAVE) and United Airlines (UAL). Names in the cruise space include Carnival (CCL, CUK), Norwegian Cruise Line (NCLH) and Royal Caribbean (RCL).