By David Shepardson

WASHINGTON, April 2 (Reuters) - The U.S. Centers for Disease Control and Prevention on Friday said fully vaccinated people can safely travel at "low risk" after the agency had held off for weeks on revising guidance that discouraged all non-essential trips.

The announcement lifting the agency's guidance that all Americans should avoid non-essential travel should be a shot in the arm for a U.S. travel industry still significantly struggling since the COVID-19 crisis began in early 2020. The new CDC guidance specifically greenlights vaccinated grandparents getting on airplanes to see grandchildren.

A group representing major U.S. airlines including American Airlines, Delta Air lines, United Airlines Southwest Airlines and other trade groups on March 22 had urged the CDC to immediately update its guidance to say "vaccinated individuals can travel safely."

The new guidance will also say fully vaccinated people do not need to get a COVID-19 test before or after travel and do not need to self-quarantine after travel.

The CDC said grandparents that have been fully vaccinated can fly to visit grandkids without getting a COVID-19 test or self-quarantining as long as they follow CDC advice for traveling safely.

But the administration is not lifting restrictions that bar most-non U.S. citizens from the United States who have recently been in China, Brazil, South Africa and most of Europe. It is also keeping requirements that nearly all international U.S. air visitors getting a negative COVID-19 test before traveling to the United States.

The CDC did not revise guidance for non-vaccinated people.

"Vaccines can help us return to the things we love about life, so we encourage every American to get vaccinated as soon as they have the opportunity," CDC director Rochelle Walensky said in a statement

The CDC's new guidance says fully vaccinated people do not need COVID-19 tests before international travel unless it is required by the international destination and vaccinated people returning from foreign travel do not need to self-quarantine after returning to the United States, unless required by state or local authorities.

The CDC had repeatedly declined in recent weeks to change the guidance and repeated it was still discouraging all non-essential travel because of a concern about new variants.

Many Americans have not been heeding the CDC's advice. The Transportation Security Administration screened 1.56 million people at U.S. airports, just below Sunday's 1.57 million, which was the highest daily total since March 2020. The last time the number of airport passengers screened was below 1 million was March 10.

The Biden administration has taken steps to reduce international travel and mandated masks in nearly all forms of public transit. The administration is not eliminating any mask rules. (Reporting by David Shepardson Editing by Chizu Nomiyama)