TOKYO—A Kobe University doctor touched off a furor with a firsthand account of a virus-stricken cruise ship in which he said the protections against infection were so weak he was scared he would get sick himself.

Kentaro Iwata, who made the allegations in widely circulated YouTube videos after spending Tuesday aboard the Diamond Princess, told The Wall Street Journal in an interview that the crew should be removed as soon as possible because of the danger of catching the novel coronavirus on the ship.

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