Norwegian Cruise Line Holdings /zigman2/quotes/204183397/composite NCLH -5.33% said Monday it will no longer require vaccinated cruise ship guests at least 12 years old to show a negative COVID test, or to have any COVID-19-related pre-boarding protocols. Meanwhile, unvaccinated guests at least 12 years old will still have to show a negative PCR or Antigen test no more than three days before they board. The cruise operator's moves come after the Centers for Disease Control and Prevention said in July that its COVID-19 Program for Cruise Ships is no longer in effect, and that COVID-19 protocols were up to individual companies. Carnival Corp. /zigman2/quotes/202325446/composite CCL -6.82% and Royal Caribbean Group /zigman2/quotes/208854639/composite RCL -7.91% have said in late July that they were dropping COVID-19 testing requirements for vaccinated guests, for cruises of less than six nights. Over the past three months, Norwegian's stock has tumbled 27.7%, Carnival shares haves shed 38.3% and Royal Caribbean's stock has tumbled 43.2%, while the S&P 500 /zigman2/quotes/210599714/realtime SPX -2.11% has gained 0.5%.