Medical expert explains whether or not it is safe to travel this summer

(CNN) – As more people get vaccinated against COVID-19 and coronavirus infection rates decline in many parts of the world, people are beginning to travel again in greater numbers.
The European Union announced the lifting of restrictions for visitors from more than a dozen countries, including the United States. Cruises from the United States will also be sailing again soon.

What must be taken into account when deciding whether and where to travel this summer? And if you are traveling with children who cannot yet be vaccinated, what additional considerations should they have?

We asked CNN Medical Analyst Dr. Leana Wen for her input. Wen is an emergency room physician and visiting professor of health policy and management at the Milken Institute School of Public Health at George Washington University. She is the author of the forthcoming book «Lifelines: A Doctor’s Journey in the Fight for Public Health«.

These are their tips:

CNN: Is it safe to travel abroad this summer, or is it safer to stay close to home?

Dr. Leana Wen: It depends. Two important factors must be taken into account. The first is your vaccination status. If you are fully vaccinated, unless you are severely immunosuppressed, you are well protected against COVID-19, and I hope you will return to the activities you love, including international travel.

On the other hand, I advise those who are not vaccinated to refrain from non-essential travel, both within and outside the country. If you are in a large crowd of people in a confined space, for example at airports or train stations, there are likely other unvaccinated people as well. They will pose a risk to you, and you will pose a risk to them.

Second, consider the destination. Many countries now allow travelers from the United States to enter, but they may still have rules that make you rethink your trip. For example, there may be a mandatory quarantine period during which you cannot visit any tourist destination. If the quarantine period is essentially the length of your trip, it may not be worth going.

You should also look up the coronavirus transmission figures. You don’t want to go to a country in the middle of a huge wave of cases. Not only would you be at risk of contracting the virus, but if you got sick, it could be difficult to find medical care. Countries with a high level of COVID-19 infections could also impose closures and other restrictions that would make your travel difficult. Depending on the current conditions, you might even have a hard time returning to the United States.

The U.S. Centers for Disease Prevention (CDC) maintains a updated list of countries by risk level. Check this list, and note that it is constantly changing. Once you decide on a destination, check the rules before you go, for example if you need to undergo tests.

If you are not a US citizen or do not have a green card, be sure to check the rules on returning to the United States. Some foreign nationals living in the United States have had their entry into the country restricted during the pandemic, and you don’t want to be accidentally trapped elsewhere.

From a logistical point of view, it is definitely easier to travel within the country. On the other hand, there are plenty of countries with low enough covid-19 rates and favorable regulations that will welcome international visitors.

CNN: Is it safe to travel by plane?

Wen: When passengers wear masks on airplanes, the transmission rate of Covid-19 is low. I have little concern about vaccinated people traveling by plane, although I would advise them to keep wearing their mask during the flight and to limit the time they spend in closed and crowded places before and after the trip.

I do worry about unvaccinated people who travel by plane. Although masks are a must on flights, many people have let their guard down and are not as cautious as they used to be. Ideally, the traveler should be vaccinated before embarking on the trip. Unvaccinated persons should wear a high-quality mask (ie an N95 or KN95) or a double mask throughout the flight.

CNN: Is it safe to travel by plane for children under the age of 2, or for other children who simply cannot keep a mask on?

Wen: I have a 1 year old girl and I don’t take her on flights. My almost 4-year-old son wears the mask quite well, and if we had a short trip, an hour-long flight, for example, I would consider taking it. But we would not cross the country or make an international flight at this time.

Other families will make different decisions. This is an in-between moment when people will make different decisions based on their perception of risk and their individual circumstances.

CNN: You’re going to say no to cruises for unvaccinated people, too, right?

Wen: Yes. Let’s take a step back and look at the unique characteristics of cruise ships. In the pre-pandemic era, the experience of a cruise ship meant that thousands of people were close to each other, with a lot of mixing, and for long periods of time.

Food, shows, drinks and dances are shared. The cruise ship makes stops along the way, and passengers often disembark and interact with people from other regions of the country or the world. They may buy souvenirs, visit attractions or hit a bar, and then come back aboard the ship to interact again.

These are some of the highest risk scenarios for the transmission of covid-19. We saw it at the beginning of the pandemic, when more than 800 people were infected aboard three cruise ships. An outbreak on a single cruise ship, the Diamond Princess, sickened more than 700 people; nine died.

Studies show that vaccination dramatically reduces the chance of contracting COVID-19 and transmitting it to other people. Even if someone vaccinated does contract the coronavirus, they most likely have a much lower viral load and cannot infect many others.

If there is a cruise of only vaccinated people, the chance that they will endanger each other is low. It is not zero, infections could occur among fully vaccinated people, but the possibility of an overspread event occurring is much lower.

However, if those on board are not vaccinated and someone ends up contracting COVID-19, that infection could spread among the unvaccinated. There is also the possibility that those vaccinated are at the same risk, particularly the elderly and those with some degree of immunosuppression.

Bottom line: If you are considering a cruise and are vaccinated, choose a cruise that requires proof of vaccination. If you are not vaccinated, do not go to the cruise, for your own safety and that of other passengers.

CNN: What if cruise ships allow children and other unvaccinated people on board as long as they have a recent negative test? Is that enough?

Wen: A negative test is definitely better than nothing, but it does not replace the need for vaccination. After all, the person could still harbor the virus, but it has not yet been detected by the test, and could still become infected during the trip.

Some cruises allow the entry of unvaccinated people, with limitations. For example, they are supposed to continue wearing masks in public places, and access to certain dining hours or indoor areas or activities could be restricted. I still think this is not enough. I would not take unvaccinated children on a cruise right now.

CNN: There is a lot of talk about the variants, especially the delta variant, which has become the dominant one in some countries and is likely to become the dominant one in the United States. Should concern for these variants influence the decision to travel?

Wen: For the vaccinated, no. The vaccines that we have in the United States are very protective against the variants identified so far.

People who are partially vaccinated, who have received only one dose of the Pfizer-BioNTech vaccine or the Moderna vaccine, need to be concerned. This is because one dose only provides 33% protection against the delta variant. And those who are not vaccinated should be concerned about this variant which is more transmissible and possibly more deadly than the other coronavirus strains.

CNN: Given that capacity restrictions have been lifted in many places, is it really safe to eat in a crowded restaurant and go to an indoor concert if you are vaccinated?

Wen: None of these activities is risk-free. If proof of vaccination is required in any of these places, that immediately reduces the risk substantially. Concerts where there are only vaccinated people will be much safer than otherwise: think about the risk of exposure if you are side by side with dozens of unvaccinated fans, without masks and very excited screaming for hours.

There are two other factors to consider. First of all, what is the transmission rate in the community you go to? Some parts of the US have vaccination levels so high that the level of covid-19 is quite low, but other parts are going through active waves.

Second, each individual circumstance must be taken into account. A restaurant with a little space between tables and good ventilation will be safer than a stand-up bar that is so loud that people have to shout to be heard.