Hello,
I am just a bit confused with the requirements before returning to US. I have both shots and the booster. I heard US requires a test within one day of flight to US. Is that a PCR or rapid test? I fly from Spain but my connecting flight is in London. Also, does London have a requirement even though I am just transiting and taking my connecting flight to US? Thanks for your guidance!!
Here is the info from the CDC. A rapid antigen test is currently acceptable. https://www.cdc.gov/coronavirus/2019-ncov/travelers/testing-international-air-travelers.html#anchor_1635127081
Here is info for Heathrow. You are transiting airside. At this time no testing is required and you do not need a passenger locator form.
https://www.heathrow.com/customer-support/faq/coronavirus-covid-19
We will be traveling to Spain next month and we have ordered the Binax monitored tests and will test ourselves in our room the day before we return to the US.