Due to the discovery in the United Kingdom of the more transmissible variant of the virus that causes CoVID-19, as of 28 December 2020, the United States Center for Disease Control and Prevention (CDC) is requiring that airline companies collect US bound traveler attestations and review documentation of negative test results for Covid-19 in order for them to travel from the United Kingdom to the United States.
The compliant viral tests will be tests determined by the United Kingdom’s relevant national authority to detect SARS-CoV-2. Test results should read “Negative,” “SARS-CoV-2 RNA Not Detected,” or “SARS-CoV-2 Antigent Not Detected.” British Airways has information on obtaining compliant test results.
British Airways also has helpful information for entering the United States in its “by country” entry requirement listings. Check out also its links by city or state for Boston, Los Angeles, New York State and Philadelphia.
Test specimens will need to have been collected in the three calendar days preceding travel to yield a qualifying test result for travel to the US. The personal identifiers (e.g., name and date of birth) on the test result documentation will need to match the traveler’s personal identifiers.
CDC Order Regarding Travel to the US from the United Kingdom
This is the first time during the pandemic that the CDC has issued an order restricting travel to the US. It is also the first time that a federal order is qualifying travel for US citizens and legal permanent residents. Some US states and cities have been making similar negative Covid-19 test demands on travelers from out of state or out of country since November 2020.
The CDC issued the order "Requirement for Negative Pre-Departure Covid-19 Test Result for All Airline Passengers Arriving into the United States from the United Kingdom (UK) on 25 December." The CDC Order mandates that airlines only board passengers, including US citizens and legal permanent residents, headed to the US - if they can produce documentation of a recent negative test result - either on paper or electronically. The result must be available at the time of flight check in. Travelers transiting the UK for less than 24 hours are excepted.
• Airlines will need to receive an attestation for each traveler aged two years or older, and save the attestations for two years.
• Airlines may be “subject to criminal penalties” for failure to comply, according to the CDC Order.
• The CDC Order is subject to modification by publication in the Federal Register or by posting an advisory on www.cdc.gov.
 Centers for Disease Control and Prevention Order "Requirement for Negative Pre-Departure Covid-19 Test Result for All Airline Passengers Arriving into the United States from the United Kingdom (UK)” link located at https://www.cdc.gov/coronavirus/2019-ncov/travelers/testing-UK-air-travelers.html