GET THE TRAVEL DISPATCH NEWSLETTER  Essential news on the changing travel landscape, expert tips and inspiration for your future trips.

Some Americans are upset that they still have to show a negative test to board a flight back to the US even though other countries have lifted their Covid testing requirements.

The C.D.C. rule is so frustrating to a software engineer in Texas that he recently sent letters to the White House and several lawmakers and began encouraging others to do the same. He no longer feels that the rule provides value because the testing has not stopped variant from entering the country.

A good portion of the travel industry in the United States has made clear it feels the same way as other travelers who have posted similar comments on social media.

The Biden administration and public health officials didn't like what they saw.

On May 6, Jen Psaki, then the White House press secretary, said she was not aware of a timetable for ending the testing requirement and that the administration would base its decision on a Centers for Disease Control and Prevention recommendation. The C.D.C. is looking at different indicators to determine if testing is still necessary, an agency spokeswoman said.

Travelers say the test has changed the experience of traveling internationally.

Danielle Bradbury spent 12 days in Israel for her job developing medical devices while her husband cared for their two children back in Boston.

The United States joined a sea of countries experimenting with different ways to slow when the C.D.C. first instituted the rule that all U.S. bound travelers had to show a negative test or proof of recovery before boarding a flight. The State Department's statement suggested that the rule was meant to discourage Americans from traveling internationally. More than 300,000 new cases of H1N1 were reported on January 8th, a record for the month, as fewer than 10 percent of Americans were vaccine free.

The United States had deployed travel limitations before. In the winter of 2020, President Trump banned visitors from many countries. The testing requirement was added on top of the travel bans when President Biden took office. He expanded the ban to India.

The United States changed its stance on banning certain countries and doubled down on testing, shortening the window from three days to one day. The coronaviruses could be spread by people who werevaccinated. Unvaccinated visitors from abroad were not allowed into the country.

It depends on how you define success, said Jeremy Goldhaber-Fiebert, a professor of health policy. The testing requirement achieved that if success was reducing the number of people who flew to the United States.

He said that it prevented people who tested positive from getting on planes and that it almost certainly prevented some amount of transmission on aircraft and in airports.

The number of people who were prevented from boarding planes because of Covid is not known. Most of the evidence is anecdotal; lots of people have stories about testing positive.

The chair of lab medicine and pathology at the Mayo Clinic said that keeping new variant out of the country failed if success meant keeping new variant out of the country.

He said that none of the measures have prevented the rapid global spread of any concern.

If success was not preventing the arrival of new variant, but instead delaying their arrival so that hospitals and authorities could be more prepared, then it may have worked. Mark Jit, a professor of vaccine epidemiology at the London School of Hygiene and Tropical Medicine, has studied the effectiveness of travel requirements and said that this is what testing does well.

He said that testing could prevent the peak from being reached so quickly.

He found that a travel test has little effect when a variant is widespread.

Explanations from authorities include readiness to enter a new phase of the Pandemic, high vaccination rates and a determination that new variant are manageable.

The current variant is making people less ill and the number of people being admitted to intensive care is limited, according to the Netherlands government.

The main argument is that it isn't doing enough to rationalize the hassle.

The C.D.C. director, Tom Frieden, was one of the people who made this point.

Others argue that it doesn't make sense to make so many people suffer. Anne Wyllie, a microbiologist at the Yale School of Public Health, said that antigen tests are unreliable in the early stages of infections. The requirement was called thehygiene theater.

According to the U.S. Travel Association, the testing requirement is economically damaging. More than 260 businesses, including airlines, cruise operators, casinos, tourism boards, Disney Parks and a zoo, have signed a letter to the White House Covid coordinator, saying that the economic costs associated with maintaining are too high.

In light of the slow economic recovery of the business and international travel sectors and the improved public health metrics in the U.S., we encourage you to immediately remove the inbound testing requirement for vaccinations.

A survey commissioned by the group found that 46 percent of international travelers would visit the United States without the requirement. The Points Guy, a site that specializes in traveling with credit card points and miles, found that more than half of its readers would be more likely to travel abroad without a requirement.

Meegan Zickus, who runs a Facebook group for people with weakened immune systems, said that testing has become more important since the mask requirement went away. Most travelers are not going to bother to test or stay home if they suspect that they have been exposed to an infectious disease.

She said that the moral compass points directly to self and that the only way to protect others is through enforced testing.

When 75 percent of people are not wearing a mask, it can give a high level of reassurance.

Research shows that people sitting within a few rows still pose a risk to one another, even though airplane ventilation systems seem to reduce the spread of the coronaviruses.

Some testing is better than none, according to Nathaniel Hafer, a geneticist at the University of Massachusetts medical school.

The Migration Policy Institute tracks travel requirements and says that many countries use testing to encourage vaccination. Most unvaccinated visitors from abroad are not allowed into the United States.

The requirement to wear a mask on airplanes and other forms of transport was in April, so some wonder if it will be struck down by a judge's decision.

Lawrence O. Gostin is a professor of global health law at Georgetown Law. The Public Health Service Act was created to prevent the introduction of dangerous infectious diseases in the United States, so the C.D.C. can require testing for visitors from abroad.

The rule would be difficult to challenge in the courts, even for the most conservative judges, he said.