CDC clarifying test requirements
 

Here are the CDC’s clarifying testing requirements for return travel to the USThe guidelines, which clarify existing CDC policies, state that travelers who present a negative COVID-19 test are subject to meeting five requirements:

• The test must be a viral test, such as a nucleic acid amplification (NAAT) or antigen.
• The test must be negative.
• The test must also include where the test was performed and the name and contact information for the lab or healthcare provider who performed the test.
• The test must be collected three days or less before flight departure to the U.S.
• The test must include information that identifies the person and must have the person’s name and at least one additional identifier such as date of birth, age, and passport number.

A LOT can happen to someone in three days.

I assume the thinking is that if someone was negative on day zero, they won't be infectious on day three in the plane. I further assume quarantine on arrival for the rest of the incubation period of a theoretical infection after the negative pre-flight test.

For better safety, don't travel unvaccinated.