In an update on the agency's website, anyone traveling within the United States may want to consider "getting tested as close to the time of departure as possible," and no more than three days before a flight. It previously only recommended testing for people who have not received COVID-19 vaccines or up-to-date booster shots.

The CDC update is also recommending that people take a test before or after a trip if they went to crowded spaces "while not wearing a well-fitting mask or respirator."

In April, a Florida federal judge struck down the CDC mandate that required people to wear masks inside airports or on airplanes. Justice Department officials have signaled they will challenge the rule, implemented after President Joe Biden took office in early 2021, in court.

A spokesperson for the agency told AFAR Magazine on May 19 that "COVID-19 vaccines are effective at preventing severe disease and death," but added, "since vaccines are not 100 percent effective at preventing infection, some people who are up to date can still get COVID-19."

"People who are up to date with their COVID-19 vaccines may feel well and not have symptoms but still can be infected and spread the virus to others," the spokesperson said.