First published: December 2020. Last updated: April 2, 2021
The United States government is not requiring citizens to take the Covid-19 vaccines. In time, though, it's almost certain that other countries, institutions, and travel businesses will.
Some airline executives have gone on record to state that in the future, their planes will only accept passengers with proof of vaccination. Theme parks around the world are also looking into vaccination as a condition for entry, and cruise lines have already announced such a demand.
It seems clear that a traveler's need for vaccination is likely to vary depending on the mode of transport and the final destination. Even if the shots aren't a requirement, they'll probably be the key to easier entry.
What's not so clear is how long after vaccination you have to wait to undertake nonessential travel.
Based on current knowledge, here's what experts are saying.
The risks for you
First, you should receive all doses before deciding anything. According to official health guidance in the United Kingdom, Pfizer/BioNTech's vaccine was designed to be given in two doses 21 days apart, while AstraZeneca's involves two injections spaced between 4 and 12 weeks apart. The Moderna vaccine comprises two doses spaced 28 days apart. The Johnson & Johnson/Janssen formula only requires a single dose and is also thought to be fully effective after two weeks.
Although some people have regarded their first dose as a license to travel and party, don't try to resume normal life in between doses—there isn't enough evidence showing that you'll be completely safe.
When the vaccines were first introduced, the Centers for Disease Control and Prevention in the United States advised against travel because at the time, it was unknown whether being vaccinated prevented people from spreading the disease without knowing it.
As the New York City Department of Health put it, we don't even know yet "whether or how often you may need to get revaccinated."
For all those reasons, Johns Hopkins advised that "until more is understood about how well the vaccine works, continuing with precautions such as mask-wearing and physical distancing will be important."
Contrary to common belief, vaccinated people aren't bulletproof from infection, although those infections do tend to be milder. As Johns Hopkins Medicine explained, "A vaccine that is 95% effective means that about 1 out of 20 people who get it may not have protection from getting the illness."
That was a common theme in the medical community. From the website of the renowned Mayo Clinic: "Experts want to learn more about the protection that a Covid-19 vaccine provides and how long immunity lasts before changing safety recommendations."
For several months, the medical community explored the potential of vaccinated people being able to sicken others without knowing. But in March 2021, a CDC study based on clinical data of the Moderna and Pfizer-BioNTech formulas determined that transmitting the disease from a vaccinated person to an unvaccinated person is extremely unlikely.
By early April, the question had been answered to the CDC's satisfaction, and it changed its guidance to say that people who have waited two weeks after their final dose are considered fully vaccinated and are eligible to travel, at least within the United States.
However, the CDC maintains that fully vaccinated people should not yet travel internationally. According to official guidance released April 2, "International travel poses additional risks and even fully vaccinated travelers are at increased risk for getting and possibly spreading new Covid-19 variants." Anyone who leaves the United States must still present a negative Covid-19 test to come back, even if they have been vaccinated.
The CDC also continues to recommend masks, social distancing, and careful hand washing whenever vaccinated people mingle with others.
The risks for others
Another reason why a needle jab shouldn't immediately set would-be travelers free to roam has to do with math.
If everyone in your family has been vaccinated, it follows that you'd be able to resume normal interactions within that social bubble. The CDC agrees with that, but when you leave that cloistered group, there's the matter of all the strangers you'd come in contact with on your travels.
Eventually, scientists hope, enough of the population will have received the vaccine that the likelihood of encountering Covid-19 in public diminishes to an acceptable risk level. That's the concept—much discussed, little understood—known as herd immunity.
The World Health Organization says that with a disease like measles, 95% of the population needs to be vaccinated before the remaining 5% of unvaccinated people are deemed to have sufficient protection. For polio, the percentage is much lower—about 80%.
The U.S. Centers for Disease Control doesn't stick by a firm target figure for Covid-19. From the agency's website: "Experts do not know what percentage of people would need to get vaccinated to achieve herd immunity to Covid-19."
In late November, America's top infectious-disease doctor, Anthony Fauci, said, "I would imagine it’s somewhere between 75% and 85% at least." But that was before the emergence of new, more transmissible strains of the Covid-19 virus made the calculations more complicated.
Many governments and businesses may choose to delay opening fully until herd immunity is reached.
That's not just conjecture. Australian Medical Association president Omar Khorshid recently told reporters that he expects his country's required 14-day arrival quarantine system to remain in place "until we have at least all of our vulnerable population vaccinated, and possibly the entire population." Khorshid's opinion was echoed by the heads of several Australian states, which set quarantine rules there.
So it's possible to travel after vaccination—but there isn't evidence that you will be fully protected from all strains, and you'll still have to follow all local health restrictions and protocols.
For full protection as we move around the world, we have to wait for herd immunity, which means vaccinating as many people as possible.
Will you be allowed to travel freely once you've got your vaccine? That all depends on how much risk governments and businesses are willing to accept.
Because of overburdened health care systems and the lingering potential for outbreaks, don't expect every place to welcome vaccinated people with open arms until herd immunity has been achieved. Until then, test results will remain a crucial gatekeeper.
Vaccines can clear individuals for takeoff. But it will take all of society to get us moving down the runway.
