'Freewinds', the quarantined vessel, was banned from departing passengers in ports when a crew member was diagnosed with measles and who aboard has previously been vaccinated against the highly contagious disease.

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Merlene Frederick-James, the island’s chief medical officer, noted that the St. Lucia Ministry of Health ordered the restriction after conferring with the Pan American Health Organization and others about the risk of exposure to islanders.

The incubation may last up to 21 days after the exposure, with infected individuals most contagious from four days before the onset of tell-tale measles rash - while the person is experiencing cold-like symptoms - to four days after the rash appears.

Now, epidemiologist Dr. Izzy Gerstenbluth, who led the team, informed that 91% of those onboard are protected against measles. This means that they do not have the risk of contracting the disease, and what is more they are no threat to transmit the disease to others. For this reason, they are free to leave the ship, Dr. Gerstenbluth explained to CNN affiliate Telecuracao.

In fact, 199 of the 216 crew members and 91 of the 102 passengers were vaccinated or were immune, and had sufficient levels of antibodies against measles.

However, some of those onboard are in quarantine, and they are retested at a local laboratory.