COVID-19 Aboard

Mitigating the spread of COVID-19 on vessels


covid 19 aboard
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Over the past year, most everyone on the planet has spoken or heard mention of the word “COVID-19” daily. However, many conversations about COVID-19 end in questions instead of clear-cut answers. As the medical community continues to learn more about the causes and effects of the virus, we all become better equipped to slow its spread. The transmission of SARS-CoV-2 (better known as COVID-19) on ships is particularly concerning because of limited space to quarantine and the isolation from immediate emergency medical care if needed.

“The most important thing is to try and keep well mariners well and keep those who are ill away from others on the vessel,” says Robert “Bob” M. Bourgeois, MD, MPH, FACOEM. “Many large employers have a good relationship with an occupational medicine physician or physician with a lot of maritime medical experience. These physicians have been able to wade through the multitude of COVID-19 studies – some of which are not scientific – and go through and find what is real and not real and coupled with real-time recommendations from WHO (World Health Organization), IMO (International Maritime Organization) and CDC (United States Centers for Disease Control and Prevention) and others, they can figure out how to implement good screening and protection programs.”


“The challenge has been ‘what do we do with the people who get sick on the vessel?’ We have the challenge of trying to quarantine them until they get transportation off the ship and keeping the rest of the crew healthy,” says Tony Alleman, MD, MPH.

The worse-case scenario: someone gets sick with COVID-19 once the ship has left the dock, despite all the screening and precaution – something slipped through the cracks. According to the CDC, “On non-cruise ships, all crew members are considered close contacts if a person with known or suspected COVID-19 is on board or disembarked within the past 14 days.” See the chart on page 28 for CDC recommendations on how to handle infection aboard.

“On some of the larger vessels, and some of the offshore installations when you may have 200 people on the vessel, some have had to be medevacked for medical assistance,” says Dr. Bourgeois.

Once an infection has been discovered, the next step is to test crew members. However, it is important to administer the PCR lab test and not the rapid antigen test (especially for asymptomatic individuals). “Antigen testing is not a good screening tool in asymptomatic individuals because they are only about 40% sensitive, which means you are only going to be able to pick four in 10 positive cases, which is not good,” Dr. Bourgeois explains.

Crew members can distance themselves as best they can, and masks are highly recommended. “Most of the HVAC systems are closed units, and the air is going out through the entire vessel, so trying to quarantine or isolate folks is a little bit of a challenge,” warns Dr. Bourgeois.


“I view a vessel as being another house, and everybody that boards the vessel is in the same household. In this case, if they recognize symptoms of COVID before they get on, then that is one way to mitigate the spread. If they have shortness of breath, fever or cough, then they shouldn’t even get on the vessel,” Dr. Alleman advises.

The old saying, “an ounce of prevention is worth a pound of cure,” holds its water in this case – and also saves lives. “Self-quarantine pre-embarkation and screening – whether it’s a screening questionnaire, temperature checks and PCR [test] before they go out – those certainly have their value. Also, masking has an important role as does social distancing. And now vaccines,” Dr. Bourgeois says.

Also, increasing makeup air in HVAC systems can reduce transmission. “HVAC systems have closed systems, but you can increase makeup air, which creates more fresh air, but it takes more energy and more time to cool it,” Dr. Bourgeois suggests.

CDC guidance suggests preventive measures to mitigate COVID-19 spread including:

  • Training of all crew on COVID-19 prevention and mitigation.
  • Avoid sharing personal items with other persons, such as blankets, laptops, tablets and other hand-held devices, and video games.
  • Wear a facemask or cloth face covering when outside of individual cabins.
  • Maintain a distance of at least 6 feet (2 meters) from others when working or moving through the ship. Note: If a 6-foot (2-meter) distance cannot be maintained in narrow corridors, then allow persons to pass completely before entering.
  • Avoid physical contact with other people, including shaking hands, giving hugs, and cheek kissing.
  • Avoid touching eyes, nose and mouth with unwashed hands.
  • Wash hands often with soap and water for at least 20 seconds.
  • Use hand sanitizer (containing greater than 60% ethanol or 70% isopropanol) if soap and water are not available.


“If you can’t catch it, you can’t spread it,” says Dr. Bourgeois, who advocates vaccination in healthy individuals.

The best prevention of COVID-19 is vaccination. “The good news is if we get more people vaccinated, we’re going to have less of this to deal with,” Dr. Alleman says.

Some contractors and companies are contemplating mandatory vaccination to return to work. “I do not see mandatory [COVID-19] vaccinations coming although I’ve heard some of the companies proposing that, at least for some of their employees,” Dr. Alleman says. “Now having said that, if somebody is healthy, has no medical problems, there’s really no reason for them not to get a vaccine.”

For individuals deciding on whether to get the vaccine, the benefits are greater than the risks. “We know that if you have the vaccine, you won’t be as sick as you could have been without it, so you’re not going to end up in the ICU,” Dr. Bourgeois says. “If you have the vaccine, you won’t have to quarantine before you go offshore and miss a few days at home with your family. If you have the vaccine, you don’t have to quarantine every time you’re around somebody who was positive.”

Looking into the future, Dr. Alleman says there are still a lot of questions. “We don’t know the effect of the mutations [of the virus] on the vaccines that we currently have,” he explains. “You might need a booster shot of the same vaccine. Or even new vaccines will need to be developed every year, similar to flu shots. But we don’t know because it hasn’t been long enough.”

Interestingly, some countries are approaching the possibility of herd immunity, which occurs when a large portion of a community becomes immune to a disease, making the spread of disease from person to person unlikely. “I was on a call this morning with people from around the world and all in the diving community. Some of these countries have already gotten 70% of their population vaccinated, and their numbers have taken a nosedive,” Dr. Alleman says. “I see the United States as being a little resistant, and we’re going to take a lot longer to get our herd immunity than those countries where most of their population is getting vaccinated.”