The Biden administration dropped the COVID-19 testing requirement for inbound international air travelers on Sunday, ending one of the longest-running travel restrictions of the pandemic.

The U.S. Centers for Disease Control and Prevention (CDC) said it will continue to monitor the state of the pandemic and will reassess the need for a testing requirement if the situation changes.

"This step is possible because of the progress we've made in our fight against COVID-19," said U.S. Health Secretary Xavier Becerra.

Airline and tourism groups have been pressing the administration for months to eliminate the testing requirement, saying it discourages people from booking international trips because they could be stranded overseas if they contract the virus on their trip.

Roger Dow, president of the U.S. Travel Association, called lifting the testing rule "another huge step forward for the recovery of inbound air travel and the return of international travel to the United States."

Airlines argued that the rule was put into effect when few Americans were vaccinated – now 71 percent of those 5 and older are fully vaccinated, according to CDC figures. They also complained that people entering the U.S. at land borders are not required to test negative for COVID-19, although they must show proof of vaccination.

While domestic U.S. travel has returned nearly to pre-pandemic levels, international travel – which is very lucrative for the airlines – has continued to lag. In May, U.S. international air travel remained 24 percent below 2019 levels, with declines among both U.S. and foreign citizens, according to trade group Airlines for America.

Some infectious-disease experts said they were comfortable with the CDC's decision, and that lifting the restriction is unlikely to cause further spread of the virus in the U.S. 

Dr William Schaffner of Vanderbilt University said the rule was designed to prevent importing the virus, "but we've got plenty of COVID-19 here. It's like telling someone not to pour a bucket of water in their swimming pool."

Dr Peter Chin-Hong at the University of California, San Francisco, said travel restrictions demonstrate that officials are trying to keep variants out, "but they haven't really shown to be beneficial, ever."

However, he said, requiring foreign visitors to be vaccinated makes sense to avoid straining the U.S. healthcare system with people who could develop severe disease.

The requirement for a negative COVID-19 test before flying to the U.S. dates back to January 2021 and was the most visible remaining U.S. travel restriction of the pandemic era.

U.S. airlines estimate that dropping the test requirement will mean 4.3 million more passengers in one year.

It is unclear, however, whether airlines can boost flights quickly enough to handle that kind of increase. Airlines facing a shortage of pilots have already scaled back their original schedules for the peak summer vacation season.

Hotels, theme parks and other travel businesses also lobbied the administration to drop the rule.

"The whole industry has been waiting for this announcement," said Martin Ferguson, a spokesman for American Express Global Business Travel, which advises companies on travel policy.

Despite ending the testing requirement, the CDC said it still recommends COVID-19 testing prior to air travel of any kind as a safety precaution.

According to the latest weekly epidemiological update released by the World Health Organization – during the week of May 30 to June 5 – over 3 million new cases were reported globally, despite a 12 percent decrease as compared to the previous week.

Over 529 million confirmed cases and over six million deaths have been reported globally as of June 5.

(With input from AP)