As COVID-19 vaccines roll out across the U.S., more travelers are taking to the skies.
Friday marked the busiest day for the nation's airports since the middle of March 2020, when COVID-19 caused air travel to plummet.
About 1.36 million passengers passed through security checkpoints Friday, according to figures from the Transportation Security Administration. That is the highest volume since March 15, 2020, when checkpoints reported more than 1.5 million passengers.
But travel remains well below pre-COVID levels. In March of 2019, checkpoint traffic averaged more than 2 million passengers a day.
Friday's uptick comes as the total number of COVID-19 doses administered in the U.S. has climbed past 100 million and about 35 million people are now fully vaccinated. The U.S. is currently administering more than 2.3 million shots a day.
The high number of travelers also comes during a period when many students traditionally travel for spring break vacations.
Despite the growing number of vaccinated Americans, the U.S. Centers for Disease Control and Prevention is still advising people to "delay travel and stay home to protect yourself and others from COVID-19."
If people must travel, the CDC says they should get a vaccine, if possible, get tested for the virus less than three days before a trip, wear a mask and avoid crowds.
A sustained increase in air travel would be welcome news for the airline industry, which has been hammered by the pandemic.
But fears of new variants of the coronavirus may limit gains from increased vaccination. Some of those variants may be more contagious or less likely to be stopped by vaccines.
The proportion of Americans who feel the pandemic will get worse rose from 13.7% in late February to 16.3% in early March, according to survey data from Destination Analysts.
Before news of the variants arrived, "We were thinking everything was starting to go in the right direction," Roger Dow, president and CEO of the U.S. Travel Association, told NPR's David Schaper.

We should be aware of the seriousness of the problem and reduce the mobility of personnel avoid virus infections.