Now, leaders say that if 100% of a ship's crew agrees to get one of the new vaccines for COVID-19, the illness caused by the novel coronavirus, some of those restrictions will be immediately eliminated.
"These 100% crews no longer have to [complete restriction-of-movement] sequester and can relax health protection measures once at sea after a short time, based on the size of their group," Rear Adm. Karl Thomas, assistant deputy chief of naval operations for operations, plans and strategy, said Friday. "We think [that] is a huge incentive."
Nearly a quarter of the Navy's active-duty personnel have received at least one COVID-19 vaccination shot, Thomas said. About 13% of the force -- roughly 45,000 sailors -- has received both shots and is considered fully immunized, he said.
Thomas said the goal is to help Navy crews operating at sea to return to regular operations. At least two Navy ships have had sizable COVID-19 outbreaks. To avoid them, others have been spending record-setting amounts of time at sea without port calls or other breaks.
"We're constantly trying to return some normalcy to what has been a very demanding and difficult environment for our sailors," Thomas said.
Navy crews with more than 1,000 members can relax health protection measures 14 days after reaching 100% vaccination. Those measures include minimizing group events and enforcing social distancing.
Crews with between 300 and 399 people that are 100% vaccinated would be able to relax those rules after four days, and those with fewer than 300, after one day, according to new guidance.
Officials recognize that getting 100% of Navy crews vaccinated is likely to prove difficult, he added. Military leaders can't force troops to get a COVID-19 vaccine while they're under emergency-use authorization by the Food and Drug Administration as the department assesses the shots' effectiveness and side effects.
For now, leaders are working on pandemic deployment policies that reflect getting between 75% and 80% of crews vaccinated.
"We think that that's a very achievable number on ships ... and then the modeling that we're doing is really looking at is, 'What does that do to the other 25% or 20% that doesn't have the shot?'" Thomas said. "What is the risk and what type of procedures do we need to put in place to still protect those individuals?"
Navy Surgeon General Rear Adm. Bruce Gillingham also said there are indicators that, when much of a crew is vaccinated, COVID cases that do break out on a ship tend to be less severe.
Despite the desire to get as many sailors vaccinated as possible, Thomas said leaders are mindful that they can't pressure their personnel into getting the shot -- even ahead of deployments.
"It's an individual choice," he said. "... We're really trying to attack it through education and try to let them make an informed decision."
Vice Adm. Andrew Lewis, commander of U.S. Second Fleet, told reporters this month that the Navy will likely make the COVID-19 vaccination mandatory "as soon as we can."