President Biden's planned requirement for incoming international travelers to have a negative COVID-19 test within 24 hours of departing will begin Monday.

A senior administration official confirmed to Fox News Thursday that the 24-hour testing requirement, which Biden officially announced earlier in the day, will go into effect on Monday. All travelers, regardless of vaccination or citizenship status, will be subject to the changed regulation.

Previously, only the unvaccinated were required to show a negative test 24 hours prior to departure, while those that were vaccinated had to show a negative test within 72 hours.

President Biden

President Biden. (AP Photo/Evan Vucci) (AP Photo/Evan Vucci)

The changes come as part of Biden's winter plan to combat COVID-19 as cases of the Omicron variant were detected in the U.S. this week.

FAUCI DODGES QUESTION ON ILLEGAL IMMIGRANTS FOLLOWING SAME TRAVEL RESTRICTIONS AS AMERICANS: 'DIFFERENT ISSUE'

Miami International Airport

Holiday travelers push their luggage inside Miami International Airport, Tuesday, Nov. 23, 2021, in Miami. (AP Photo/Marta Lavandier) (AP Photo/Marta Lavandier)

"Experts say that COVID-19 cases will continue to rise in the weeks ahead this winter, and that we will see more omicron cases here in the United States in the days, weeks and months ahead. Our best scientists and doctors are on the case and gathering data, but early indications are that our vaccines will provide a measure of protection against this strain," Biden said in an op-ed published in USA Today Thursday.

Biden also announced a campaign to continue encouraging Americans to get vaccinated or get booster shots if they have previously received the jab, expanding access to vaccines with more walk-in appointments and longer hours and weekend availability at vaccination sites.

CLICK HERE TO GET THE FOX NEWS APP

President Joe Biden

President Joe Biden. (AP Photo/Carolyn Kaster) (AP Photo/Carolyn Kaster)

The plan also calls for insurers to pay 100% of the cost of in-home testing kits, and they will be provided for free pickup for those who do not have private insurance.

"We are going to fight COVID-19 not with shutdowns or lockdowns – but with more widespread vaccinations, boosters, testing and more," Biden said. "We will beat it back with science and speed, not chaos and confusion – just as we did in the spring and again with the more powerful delta variant in the summer and fall."