What if you're not eligible for the COVID-19 vaccine? Can you travel?

More than 21% of the U.S. population have been fully vaccinated against COVID-19. And many of the people who have been vaccinated — or are scheduled to receive the vaccine soon — are thinking about their travel plans for 2021 and beyond.

But what if you’re ineligible for the vaccine right now, for whatever reason? In that case, you still might be able to travel -- with some extra hoops. But it likely won’t be that simple, given how complex the COVID-19 pandemic is. Here’s what you need to know.

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Who isn’t eligible for the COVID-19 vaccine?

Currently, the only groups the Centers for Disease Control and Prevention (CDC) recommends postponing vaccination are people currently sick with or those who get COVID-19 before getting their second dose of vaccine. Also, people with severe allergic reactions to any component of the vaccine shouldn’t receive it. Children under 16 aren’t eligible for the vaccine yet, at all -- more on that below.

Related: US recommends pausing Johnson & Johnson vaccine: What to know about COVID-19 vaccines in the US

Can children travel abroad if they haven’t been vaccinated?

Children might be the best example of a large population of people who aren’t eligible for vaccination yet.

Currently, there’s an age limit on all three vaccines available under the Emergency Use Authorization from the Food and Drug Administration (FDA). The Pfizer-BioNTech vaccine is available for people 16 and older, while the Moderna and Johnson & Johnson vaccines are available for adults who are over 18.

Kids aren’t yet eligible for vaccination, under current guidelines, and might not be for a while. Pfizer said on March 31 that its vaccine was 100% effective in children ages 12 to 15, and the company hopes to start vaccinating this age group “before the start of the next school year.”

“Children and adolescents outside these authorized age groups should not receive COVID-19 vaccination at this time,” say guidelines issued by the CDC. The CDC also says there are limited vaccine safety and efficacy data in this age group.

Related: Can you skip quarantine if you’ve been vaccinated?

The cruise industry offers a glimpse of how the travel industry might handle travelers who aren’t vaccinated. Royal Caribbean and Celebrity said children under 18 could sail with proof of a negative COVID-19 test instead of proof of vaccination.

However, both lines said adult passengers would need to be fully vaccinated to sail when the lines resume operations in June.

Dozens of countries have now reopened to U.S. tourists. Some of those countries have already announced plans to welcome back — or waive testing and quarantine requirements for — fully vaccinated travelers.

Related: Do kids need to get the COVID-19 vaccine before traveling?

Will a vaccine be required to travel?

Several countries have indicated that they’ll allow vaccinated travelers to skip mandatory quarantines. And certain destinations and travel providers have indicated the vaccine could even be a requirement.

Having received a COVID-19 vaccine could very well be a new requirement for entry to some destinations, similar to the way proof of yellow fever vaccination is already necessary to travel to some countries.

Related: Where you can go with a vaccine passport: A country-by-country guide

What about other travel vaccines?

There’s much more guidance on people who shouldn’t take the yellow fever vaccine, for instance. How countries have handled these vaccines may serve as guidelines for overseeing people who aren’t yet eligible for vaccination.

For example, people can opt-out of taking the yellow fever vaccine if they’ve had an allergic reaction after a previous dose, have a weakened immune system or have gotten any other vaccines in the past four weeks.

But it’s not as simple as saying you can’t take it, especially for international travel.

Travelers headed to Ghana, which requires the yellow fever vaccine, are required to show a vaccination waiver issued by a medical practitioner stating the reasons why a person can’t take it. However, the International Association for Medical Assistance to Travellers, a travel health organization, notes that these waivers might not be accepted.

Bottom line

We can look to how other countries have handled entry requirements for travel vaccines, like yellow fever, to possibly predict how the COVID-19 vaccines will be handled for those not eligible to receive it.

Children might be afforded more leeway because most aren't eligible for vaccination as of yet. But if you're an adult, justifying not being eligible for vaccination might prove difficult -- if not impossible -- in some countries.