In response to the omicron variant, the U.S. Centers for Disease Control and Prevention (CDC) has significantly shortened the time period during which travelers must secure a negative COVID-19 test before traveling to the United States. All air passengers 2 years or older with a flight departing to the U.S. from a foreign country after 12:01am EST on December 6, 2021, are required show a negative COVID-19 viral test result taken no more than 1 day before travel, or documentation of having recovered from COVID-19 in the past 90 days, before they board their flight. Previously, the 1-day rule only applied to unvaccinated travelers, and vaccinated travelers were allowed 3 days before departure to secure negative test results.

This change applies to all travelers 2 years or older, including U.S. citizens and lawful permanent residents.

Similar to the previous process, the CDC will use days, rather than hours, to determine compliance with the rule. The 1-day period is interpreted to be 1 day before the flight’s departure. The CDC uses a 1-day time frame instead of 24 hours to provide more flexibility to the air passenger and aircraft operator. By using a 1-day window, test acceptability does not depend on the time of the flight or the time of day that the test sample was taken.

The new rule also takes into account possible flight delays. If the first flight in the trip is delayed past the 1-day limit of testing due to a situation outside of the passenger’s control, such as weather, and that delay is 24 hours or less past the 1-day limit for testing, the passenger does not need to be retested.

The CDC has a posted a Frequently Asked Questions page which addresses a variety of scenarios, including connecting flights and layovers.