The recommendation concerns groups of the population at high risk of developing a severe form of coronavirus.

The U.S. Centers for Disease Control and Prevention (CDC) on Friday issued a recommendation that some groups of travelers be advised to avoid tours on cruise liners and river cruises, regardless of the vaccination status.

The CDC stressed that older people and people with chronic diseases are more likely to get a serious form of coronavirus, and they need to consult a doctor before traveling.

The warning was issued against the background of an increase in cases of coronavirus on cruise liners. According to the CDC, cases of infection are caused by the Delta variant.

Recall that US cruise operators have resumed tours after lengthy negotiations with the CDC since May of this year. According to the recommendation of the American regulator, only fully vaccinated people were recommended to make trips. The crew of the ships also had to be fully vaccinated.