Cruise holidays started up again in June this year after more than a year of being consigned to land during the pandemic. They now continue to operate despite the ongoing investigation by infection disease experts.
The CDC have put at least 86 cruise ships under investigation or observation, with the New York Times COVID-19 tracker showing daily cases topping 488,000 on Wednesday after record numbers over the Christmas long weekend.
The CDC said that the seven-day average increase in infections is now the highest it has been since the very start of 2021.
The centres had already placed 48 vessels under investigation, now adding 38 to the list of those “under observation”.
Cruise ships are likely to foster the even faster spread of the highly contagious Omicron variant of coronavirus due to the limited space available and close proximity of passengers.
The CDC warned: “Cruise ships involve the movement of large numbers of people in settings where they are likely to have close contact with one another.”
They added: “Close-contact environments facilitate transmission of respiratory viruses from person to person through exposure to respiratory droplets, aerosols, or contact with contaminated surfaces.
“Cruise ships may also be a means by which infected persons travel between geographic locations.”
This comes as a Democrat senator described cruise ships as “petri dishes” for COVID-19 transmission.
Mr Blumenthal referenced an article by the Washington Post, in which a cruise ship holidaymaker described her trip on the vessel as feeling as if she had “just spent my past week at a superspreader event”.
Case numbers have shot up as the Omicron variant makes its way through American communities.
Cruise ships were among the first casualties of decimated industries as the pandemic kicked off, many marooned away from shore in March 2020 before they were allowed to dock once again.
Trips restarted in the summer after the rollout of the vaccine rollout, with many cruiseliners requiring passengers to be vaccinated to get onboard.
Around 62 percent of Americans are fully vaccinated.
Between June – when the industry was allowed to reopen – and October 21, cruise operators reported 1,359 cases of COVID-19 on board, according to CDC data.
There were 49 people hospitalised with the disease and 38 medical evacuations during this four-month period, as well as at least one death during a cruise trip.
CDC lead for its maritime unit, Aimee Treffiletti, told The Washington Post that vaccinations must continue to be a vital part of cruise operations.
She said: “That’s one of the main reasons we haven’t seen medical systems overwhelmed on board, because we have such high vaccination rates on board.”