Democrats are asking Biden to mandate that airlines require passengers to be fully vaxxed for COVID-19 before flying

• Democrats are urging President Joe Biden to mandate that domestic air travelers be fully vaccinated.
• More than 30 Democratic lawmakers signed onto the letter, sent earlier this week to Biden.

Democratic lawmakers are urging President Joe Biden to require that all airline passengers either show proof of full vaccination against the coronavirus or a negative COVID-19 test before boarding a domestic flight.

The request was made in a letter, signed by more than 30 Democrats that was sent to Biden November 11.

"This is a necessary and long overdue step toward ensuring all Americans feel safe and confident while traveling and reduce the chances of yet another devastating winter surge," the Democrats wrote in the letter.

The letter comes as millions plan to travel for the upcoming Thanksgiving holiday. An estimation from the American Automobile Association says more than 53 million people are planning to travel to see loved ones for Thanksgiving this year. Of that, about 4.2 million people are expected to travel by air.

The Centers for Disease Control and Prevention advises people to avoid taking domestic flights unless they're fully vaccinated against the coronavirus.

The White House in October announced that international travelers coming into the United States must show proof of full vaccination to enter.

The Democrats who signed onto the letter are urging that Biden expand that mandate to people traveling within the US as well to minimize the risk of spikes in COVID-19 cases after the holidays.

"We applaud your adoption of vaccine requirements for international air travelers coming to the United States," the letter says.

"It is in the best interest of our nation's public health to adopt these vaccination requirements for U.S. air travel," the letter continues.

Americans have been booking holiday flights for Thanksgiving and Christmas this year as early as March and April, Insider's Thomas Pallini reported.

Last year, holiday travel spiked despite pleas from public health officials that Americans stay home. Health officials like Dr. Anthony Fauci warned about a wave in COVID-19 cases following holiday travel.

About 60% of the US population is fully vaccinated against the coronavirus, according to data compiled by Johns Hopkins University.