People travelling to Guernsey from anywhere in the world will have to self-isolate for 14 days, from Thursday 19 March.
The States of Guernsey says a review of the latest epidemiologicalevidence regarding coronavirus and an assessment of agencies and services has resulted in this change of policy.
This new measure includes all travel, by any means including privately owned or chartered vessels and includes travel between the Bailiwicks of Guernsey and Jersey.
However, people will be able to travel within the Bailiwick of Guernsey, between Guernsey, Alderney, Sark and Herm.
An exemption list for "critical roles" to travel for reasons that are essential to the running of the island is being prepared.
Anyone in self-isolation having entered the Bailiwick who develops symptoms, however mild, of a cough, fever or shortness of breath must ring the coronavirus helpline on 01481 756938 and 01481 756969.