Travel insurance, including emergency medical, evacuation, and repatriation coverage is strongly recommended. You can purchase the Voyage Protection offered by Virgin Voyages (see below) or buy travel insurance independently.
It is highly recommended that you buy insurance within 15 days of paying your deposit in order to receive coverage for pre-existing conditions. Additional cancel for any reason protection is also recommended for more flexibility and increased protection of your investment in your trip.
Squaremouth is a great resource for researching and purchasing travel insurance.