USN: If One COVID Case is Present, Asymptomatic Cases Are On Board

Sailors from the carrier USS Theodore Roosevelt disembark to move to off-ship berthing, April 10. Nearly 600 of USS Roosevelt's 4,800 member crew have tested positive to date. (USN)

Published Apr 15, 2020 7:00 PM by The Maritime Executive

In an acknowledgement of the challenges that naval, cruise and merchant vessel operators face in keeping COVID-19 off of their ships, the U.S. Navy has released stringent new guidelines for coronavirus response in the event of an ill crewmember on board. In particular, the advisory calls on commanding officers to carry out a weeks-long quarantine period before getting under way and to act as though asymptomatic positives are on board. This means that the ship's "day-to-day actions must assume COVID is present" - a reflection of recent evidence on the high rate of patients who never develop clinical symptoms. 

The guidance - which all vessels must follow to the maximum extent possible - begins with a 14 day pre-sail quarantine period, and COs are advised to consider increasing this quarantine period to 21 days in order to catch additional cases. COs must screen their crews for underlying conditions that increase the risk of COVID-19 mortality and consider leaving these personnel on shore. 

Each time another sailor falls ill, he or she must be isolated while undergoing medical evaluation. Every person that the individual came into contact with must be screened for symptoms and quarantined for 14 days (or until cleared by medical staff). This includes individuals in the positive sailor’s berthing with an adjacent rack; anyone with prolonged interactions with the sailor in the ship's galley, gym, smoking deck, chapel, or other common area; or anyone present in the positive sailor’s immediate workspace during their infectious interval, defined as the period beginning 48 hours before the positive case developed symptoms. 

To reduce further spread, COs should consider dividing all personnel into designated areas of the ship, such as quadrants or decks, in order to minimize physical contact. Uninfected personnel should berth in known clean spaces, and the crew should be divided into cohorts with minimal interaction. Meal times should be staggered by department to reduce crowding, and chow lines should not be self-serve. Disinfection should be conducted at least three times daily, and any compartment that is known to be contaminated should be closed off for a week (if possible) in order to ensure the neutralization of residual virus on surfaces. 

The stringent measures - particularly the extended pre-sail quarantine period - are in line with recent evidence suggesting that asymptomatic cases play a major role in spreading the disease. Cruise ship outbreaks provide an exceptional example: half of the 700-plus Diamond Princess passengers who tested positive had no clinical symptoms, according to the CDC. Last week, 60 percent of the people on board the cruise ship Greg Mortimer tested positive for COVID-19, and not one had symptoms at the time of test administration, according to the vessel's operator. 

In a podcast released Wednesday, former Secretary of the Navy Ray Mabus recommended an even more aggressive approach to dealing with COVID-19 in the fleet. “What I think what they need to do is bring every ship in,” said Mabus. “Offload most of the crew . . . leave a very skeletal force on board, sanitize the ship, quarantine people for two weeks, make sure nobody’s got COVID. And then once they go back on that ship . . . they don’t get off [until after the pandemic]."