Cruise ships will be able to resume sailing in U.S. territorial waters by midsummer as long as nearly all crew and passengers have been fully vaccinated against COVID-19, the Centers for Disease Control and Prevention told the companies this week.

The new timeline puts cruises on track to resume voyages around mid-July only if 95% of passengers and 98% of crew aboard any ship have been inoculated against the coronavirus.

The Atlanta-based health agency also eased some previous testing and quarantine requirements for cruise operators to facilitate the industry.

“We acknowledge that cruising will never be a zero-risk activity,” the agency said in a letter to cruise industry officials obtained by ABC News, “and that the goal of the Framework for Conditional Sailing Order’s phased approach is to resume passenger operations in a way that mitigates the risk of COVID-19 transmission onboard cruise ships and across port communities.”

Major cruise lines have been blocked from sailing from U.S. ports since March of last year after the pandemic was declared.

The “no-sail” order was put in place as outbreaks were reported on several cruise ships around the world.

All the major cruise lines that operate in the U.S. ― Carnival, Royal Caribbean and Norwegian ― have continued to extend shutdowns month-to-month while the CDC kept the no-sail order in place.

Each company had finally hoped for a return to the seas earlier this month, but they were forced to delay as the coronavirus pandemic began surging again around the world.

The cruise industry has been pressuring the CDC to lift the conditional sail order and allow operations to resume from U.S. ports beginning in early July, calling the government order outdated and unfair.

Last week, Alaska joined a Florida lawsuit seeking to overturn the CDC mandate blocking sailings from U.S. ports.

The coronavirus pandemic has kept ships docked despite the fact that other companies around the world have resumed sailings with extensive health safety measures in place.