As summer approaches and the cruise season ramps up, travelers ready to set sail may feel uneasy due to recent hantavirus and norovirus outbreaks on cruise ships. Still, public health experts say there’s no need for alarm: While viruses can spread on cruises, traveling by sea remains safe.

Cruise ships are among the most closely inspected forms of transportation, and the Centers for Disease Control and Prevention (CDC) publishes their sanitation scores for the public. Many major cruise lines earn perfect or near-perfect ratings, but experts note these scores can’t fully predict outbreak risk. That’s why it’s essential for passengers to practice good hygiene and take preventative steps to reduce the risk of getting sick on board.

Why Viruses Can Spread So Easily on Cruises

Cruise ships aren’t any less sanitary than traveling by plane or vacationing at a resort—they just operate under different conditions. Even when ships meet high sanitation standards, they can be more vulnerable to viruses because passengers remain in close quarters for extended periods.

“On a plane, passengers typically spend just hours together, not interacting heavily, and breathing HEPA-filtered air that is refreshed 20 to 30 times per hour,” said Peter Chin-Hong, MD, an infectious disease expert and professor of medicine at the University of California, San Francisco. “Guests at a hotel or resort also differ from passengers on a cruise ship—they are not a closed and captive population and can typically come and go as they please.”

For highly contagious infections like norovirus that can spread through tiny particles of feces or vomit, cruise ships can be a breeding ground for outbreaks. Close quarters and shared surfaces mean a single case can rapidly sicken large numbers of passengers.

“Some factors that make cruise ships riskier for infectious disease are prolonged close contact with a closed population who share dining halls, entertainment areas, and recreational facilities,” Chin-Hong said.

He added that poor ventilation in crowded areas and the difficulty of isolating when someone gets sick can further raise the risk.

The In-Flight Habits That Help Frequent Fliers Stay Healthy

8 Tips to Avoid Food Poisoning on Your Next Trip

Are Sanitation Scores Reliable?

The CDC’s Vessel Sanitation Program assigns sanitation scores to every cruise ship. These scores offer a quick snapshot of a ship’s cleanliness and safety, but they don’t capture the full picture.

“CDC sanitation scores are a useful tool because they provide transparency around food safety, hygiene practices, and onboard sanitation standards,” said Bernadette Boden-Albala, MPH, DrPH, a professor and the founding dean of the Joe C. Wen School of Population and Public Health at the University of California, Irvine. “They are an important indicator, but no score can completely eliminate risk because infectious disease transmission is also influenced by traveler behavior, crowding, and how quickly illnesses are identified and contained.”

The scores also have limitations. Inspections are unannounced but occur only a few times a year, so they reflect conditions on a specific day rather than across every voyage. They also don’t account for passenger behavior.

Boden-Albala also noted that these reports could be better at outlining their efforts during an outbreak.

“One area that could always be strengthened is public communication around how ships respond to emerging illnesses in real time, including surveillance practices, outbreak response protocols, and coordination with public health authorities,” she said. “Transparency builds public trust.”

How to Protect Yourself on a Cruise

Health experts and staff members on cruise ships work hard to keep your voyage clean and safe.

“The hantavirus outbreak is a rare event,” said William Schaffner, MD, a professor of preventive medicine, health policy, and infectious disease at Vanderbilt University School of Medicine. And as for norovirus, “the cruise ship industry has infection control procedures to minimize the risk of an outbreak.”

However, Schaffner noted that there’s no harm in taking extra safety precautions, especially for young children, older adults, pregnant people, and those who are immunocompromised. Even simple preventive practices can help lower your risk of infection.

“The single most important thing is to wash hands thoroughly and frequently with soap and water for a requisite 20 seconds,” Chin-Hong said. “And remember that norovirus cannot be prevented by hand sanitizers.”

If you feel unwell on board, don’t wait to tell the medical staff on your cruise about your symptoms. Early reporting is an effective way to limit transmission to other passengers. Until a medical professional can evaluate you, isolate yourself in your cabin, and stay hydrated.

Though rare, if your cruise ship has an outbreak, stay calm, practice basic prevention strategies, and keep the medical staff informed if you develop symptoms such as vomiting, diarrhea, stomach pain, or fever.

“The vast majority of cruise ship outbreaks, like norovirus, do not lead to widespread community transmission,” Chin-Hong said. “Since COVID, cruise ships have transformed protocols to make the environment safer via pre-embarkation symptom screening, having dedicated isolation cabins and quarantine zones, and improving ventilation.”