Holiday and cruise ship operator Saga has said that all clients must produce proof of Covid-19 vaccination before taking a trip.
Saga, which specialises in holidays for the over-50s, said it wanted to protect customers' health and safety.
As things stand Saga says it will delay restarting its travel packages until May to give customers enough time to get jabs.
Currently, Saga hopes to return to service with Spirit of Adventure’s inaugural voyage continuing as planned on 4 May, with Spirit of Discovery to return on 2 June. The two sister ships are currently both berthed at Tilbury.
The Saga holidays programme will begin on 1 May with hotel stays, escorted tours and river cruises.