Potential customers must have received both shots of a vaccine at least 14 days before departure.
A spokesperson said: “The health and safety of our customers has always been our number one priority at Saga, so we have taken the decision to require everyone travelling with us to be fully vaccinated against Covid-19.
“Our customers want the reassurance of the vaccine and to know others travelling with them will be vaccinated too.
“To allow our customers time to get vaccinated, we are moving the restart date for our travel businesses to May.
“Our new vaccination policy will be in addition to the detailed arrangements we have already put in place for when cruises and other holidays restart.”
The British government is currently hoping to offer everybody over the age of 50 at least one shot of vaccine by the end of April, with the second to follow within two weeks.
Currently, Saga hopes to return to service with Spirit of Adventure’s inaugural voyage continuing as planned on May 4th, with Spirit of Discovery to return on June 2nd.
The Saga holidays programme will begin on May 1st with hotel stays, escorted tours and river cruises.