June 29 (Reuters) - Royal Caribbean International said on Tuesday it would require unvaccinated guests over 12 years of age traveling from Florida to show proof of insurance that covers COVID-19 related medical expenses, quarantine and evacuation. The new policy comes after two unvaccinated teenagers tested positive on its Adventure of the Seas ship last week and two others were infected on Celebrity Millennium earlier this month. Celebrity had said it would bear expenses for the two cases. Sailings on its new ship, Odyssey Of The Seas, was also postponed after crew members had tested positive. In Florida, the government bars companies from requiring to show proof of vaccines, making it difficult for cruise operators which, as per U.S. health regulators" orders, need to show a majority of its passengers and crew are vaccinated before setting sail. The insurance policy must have a minimum of $25,000 per person for medical expenses and $50,000 per person in travel expenses, Royal Caribbean said. Proof of travel insurance is a condition of boarding and must be shown at check in, the company said. The changes apply to trips from Aug. 1 through Dec. 31. The cruise operator"s parent Royal Caribbean Group (RCL.N) restarted sailing from U.S. ports and has a slew of trips planned after more than a year of anchoring ships. On Tuesday, Royal Caribbean"s Freedom of the Seas received a green signal from the U.S. Centers for Disease Control and Prevention, making it the cruise line"s first ship to resume sailing from the United States. Any unvaccinated guests, mainly children, will be subject to additional testing and specific health protocols, the cruise line"s chief executive officer, Michael Bayley, wrote on social media. The ship, which completed a simulated voyage earlier this month, will set sail on July 2 to the Bahamas with a fully vaccinated crew.