An American Airlines flight attendant. LM Otero/AP American Airlines' flight attendant union is telling members that they won't be immediately fired if they remain unvaccinated past the airline's deadline. All American employees must be vaccinated against COVID-19 per a Biden administration mandate for federal contractors. American's deadline for vaccination is just days before the Thanksgiving holiday. American Airlines' flight attendant union is telling flight attendants unvaccinated for COVID-19 that they won't immediately be fired or taken off flights if they don't abide by the airline's deadline to be vaccinated.The Association of Professional Flight Attendants on Monday updated its members on the status of its negotiations with the airline regarding the vaccine mandate.