Today the Centers for Disease Control and Prevention (CDC) announced that it will start requiring a negative COVID-19 test from all air passengers who are entering the United States, beginning January 26.

Since the U.S. is already in the midst of a nationwide surge, testing requirements to prevent the import of fresh infection should help to slow the spread.

With new variants of the virus cropping up around the world, some more highly transmissible than previous ones, the agency has deemed pre- and post-travel testing to be an important precautionary layer for curbing the introduction and dispersion of new strains.

“This strategy is consistent with the current phase of the pandemic and more efficiently protects the health of Americans,” the CDC wrote in its statement .

International travelers bound for the U.S. will need to test negative within the 72-hour window prior to their departure, and the CDC also recommends that they get tested again three to five days after arrival, self-quarantining for seven days post-travel.

Passengers will need to provide their documented lab results to the airline prior to boarding, either electronically or on paper, or may provide documented evidence of having recovered from COVID-19. Airlines are directed to confirm the ‘negative’ status of every passenger, and those who fail to provide documentation of their negative test or recovery, or who choose not to test, must be denied boarding.

“Testing does not eliminate all risk,” said CDC Director Robert R. Redfield, M.D., “but when combined with a period of staying at home and everyday precautions like wearing masks and social distancing, it can make travel safer, healthier, and more responsible by reducing spread on planes, in airports, and at destinations.”