(CNN) — The spread of novel coronavirus has travelers around the world on edge. Much is still unknown about the outbreak, and health officials are urging caution.
That means travelers crisscrossing the globe should be aware of the virus, steer clear of heavily impacted areas and exercise some of the same kinds of preventive measures they'd use to avoid influenza and other illnesses.
Here's what travelers should know about the virus outbreak:
Cruise ship cases
With more than 600 cases of coronavirus diagnosed on board, the Diamond Princess cruise ship has been the site of the largest outbreak of the virus outside of mainland China.
On Thursday, the deaths of two Diamond Princess passengers -- a man and a woman in their '80s -- were confirmed.
Hundreds of passengers disembarked the Diamond Princess in Yokohama, Japan, Wednesday after a two-week quarantine, with more passengers expected to disembark later in the week, according to a statement from Princess Cruises.
The US State Department evacuated more than 300 US citizens and their immediate family members from Diamond Princess via charter flights on February 16.
Of those passengers, 14 tested positive for the virus after they had disembarked the ship and were isolated in a "specialized containment area on the evacuation aircraft," according to a State Department statement.
Most of the evacuated US passengers will remain under quarantine in the United States for 14 days at military bases in California and Texas. Some of those who tested positive were transferred to University of Nebraska Medical Center in Omaha.
Another cruise ship, Holland America's Westerdam, was turned away from several Asian countries over coronavirus fears before being allowed to dock in Cambodia on February 14.
While no cases of coronavirus were initially detected upon disembarkation, one of its passengers tested positive for the coronavirus during a stopover in Malaysia the following day.
In a statement, the Holland America Line confirmed the virus case but was insistent that everyone on the ship had been screened on February 10, five days before the positive diagnosis.
Cruise line precautions
Cruise Lines International Association (CLIA) has issued enhanced protocols for its members in efforts to prevent introduction of the illness aboard ships.
"The health and safety of cruise passengers and crew is and remains the number one priority of CLIA and its member lines, which make up over 90% of ocean-going cruise capacity worldwide," CLIA said in a statement.
"CLIA members are to deny boarding to all persons who have traveled from, visited or transited via airports in China, including Hong Kong and Macau, within 14 days before embarkation," one of the organization's guidelines reads.
Denied boarding for anyone who has had close contact with anyone suspected to have coronavirus and pre-boarding screening are also outlined.
Individual cruise lines also have their own policies and screening procedures to guard against introducing the illness.
Travel advisers are seeing the most concern among travelers with trips planned to Asia in the next few months.
Even in Asia, the probability of encountering someone who has been exposed to the virus, is asymptomatic upon getting on the ship and developing symptoms over the course of a trip is "really, really low," according to Dr. John Lynch, who has specialties in infectious disease and travel medicine at University of Washington School of Medicine.
"I think there's extremely low risk of getting novel coronavirus on a cruise ship," said Lynch.
Cruises to and from mainland China have been canceled, according to Cruise Critic, an online cruise community and review site. Many other sailings in the region have been modified or canceled due to virus concerns.
US escalates precautions to stem spread of virus
Any US citizen who has been in China's Hubei Province in the last 14 days is subject to up to 14 days of mandatory quarantine upon return to the United States, according to Department of Homeland Security rules implemented at the beginning of February.
US citizens who have been to the rest of mainland China in the last 14 days must undergo screening at one of 11 designated US airports and up to 14 days of self-quarantine.
The new rules also mean most foreign nationals who were recently in China will be temporarily denied entry into the US.
Advisories warn against travel to China
On February 19, the CDC issued new travel advisories for Hong Kong and Japan -- its first coronavirus-related travel warnings outside of mainland China. The health agency put advisories for those two locations at Watch: Level 1, advising travelers to "practice usual precautions."
These precautions include avoiding contact with sick people and regularly and thoroughly cleaning hands. The agency also advises people to seek medical advice if they have spent time in Hong Kong or Japan during the last two weeks and feel ill with fever or respiratory symptoms.
The CDC "does not recommend canceling or postponing travel" to Hong Kong or Japan at this time, the agency posted on its website.
The World Health Organization declared the novel coronavirus outbreak a public health emergency of international concern, after an emergency committee reconvened on January 30 in Geneva.
The CDC is warning against all nonessential travel to China.
Flights to China suspended
Airlines all over the globe have canceled flights amid the outbreak.
The International Air Transport Association (IATA) estimates that the total global lost revenue for airlines could be $29.3 billion due to coronavirus.
American Airlines also suspended flights between the US and China through March 28. American has also canceled some flights to Hong Kong.
Other airlines, including British Airways, Lufthansa, Air France, Air Asia, EgyptAir, Cathay Pacific, Air India and Finnair have similarly slashed or suspended service.
Many airlines have offered waivers on change fees or the option to cancel for credit on a future flight.
Travelers with upcoming plans should check with their airlines and look for advisories posted on carriers' websites.
Most travel insurance is unlikely to cover this situation
Airlines are relaxing their policies and some major hotel chains are waiving cancellation fees, but recouping all the costs associated with trips canceled due to coronavirus fears is far from guaranteed. An outbreak of a virus is not covered under most standard trip cancellation insurance policies, according to TravelInsurance.com.
"For those who purchased a Cancel for Any Reason (CFAR) optional upgrade, however, some measure of trip cancellation protection may be available," according to Stan Sandberg, co-founder of TravelInsurance.com.
"For those holding an existing travel insurance policy, they should contact their travel insurance providers to find out if their plans have any coverage," Sandberg advises.
Advice for travelers who cannot avoid travel to China
Travelers who cannot delay traveling to China should practice enhanced precautions by avoiding contact with sick people, animals and animal markets and frequently and thoroughly washing hands, the CDC recommends.
The CDC advises washing hands often with soap and water for at least 20 seconds. An alcohol-based hand sanitizer with at least 60% alcohol can be used when soap and water are not available.
Discuss travel to China with your healthcare providers, the CDC advises, noting that older adults and travelers with underlying health issues may be at higher risk.
Travelers who've visited China within the past two weeks and who are feeling sick with fever, have a cough or difficulty breathing should seek treatment right away and call ahead to tell medical providers about recent travel to China and symptoms.
The CDC also advises potentially infected travelers to avoid contact with others, to not travel while sick and to be sure to cover your mouth and nose with a tissue or your sleeve (not your hands) when coughing or sneezing.
Some of the above precautions apply to all travelers, particularly during winter respiratory illness season.
Some US airports have implemented health screenings for travelers arriving from affected areas of China.
David McNew/Getty Images North America/Getty Images
Hand washing is a strong defense; masks are less effective
Dr. William Schaffner, a professor of medicine in Vanderbilt University's division of infectious diseases, has received a lot of questions about whether people should be wearing masks to avoid infection.
He realizes it's culturally very common in Asia, but he says the CDC doesn't recommend it for the general public because "the scientific basis showing that people in the community wearing masks actually has any benefit is very thin and questionable."
More fitted respirator masks may be used in medical settings, but are generally impractical for the general public, Schaffner says.
Good hand hygiene is a better defense.
Air travel is part of how viruses spread
For parts of the world outside of the heavily affected region, air travel is likely where more of the risk will lie, says Dr. Yoko Furuya, because of the increased likelihood of encountering international travelers from areas with high incidence of the virus.
"When it comes to the global spread of outbreaks, air travel is usually how things kind of spread quickly from country to country," says Furuya, associate professor of medicine in the division of infectious diseases at Columbia University Irving Medical Center.
Schaffner says the spread of winter respiratory illnesses on airplanes is always a concern. "More than once, I'm quite certain personally that I have acquired a winter virus on the aircraft while traveling or working my way through crowded airports," he says.
Frequent and vigorous hand washing is again critical to reducing viral transmissions.