Hello, apart from proof of vaccination, do US citizens also need COVID tests to enter Paris?

Not to enter Paris but you do need one for transiting Heathrow.

Here's the current rules per Heathrows website:

Transiting passengers
All international arrivals are required to present a negative COVID-19 test, taken no earlier than three days before departing for England. This applies to passengers transiting the UK.

If you are transiting through the UK to another international destination, you do not need to quarantine or take a COVID-19 test on arrival or on day 2 and day 8; but you must present the following to your airline before departure:

Complete a Passenger Locator Form
Provide proof of a negative COVID-19 test (taken within three days of departure)

French entry requirements are not based upon citizenship, only the country from where you enter France.

Entering from the UK, you must follow amber/orange country entry requirements, which are:

1. proof of vaccination
2. completion of a sworn statement certifying the absence of COVID-19 symptoms and of any contact with a confirmed case of COVID-19. A copy of the statement is available here.

French entry requirements are not based upon citizenship, only the country from where you enter France.

and where you have been in the past 10 days, n'est pas?

As of Monday, 10/4 you do not need a pre-travel test to enter the UK. If you remain, airside and don't plan to enter the UK, you don't need to arrange for a Day 2 test.

No test is needed to enter France. Just your CDC card and a passport. Oh, and a form to fill out.

https://www.gov.uk/guidance/red-amber-and-green-list-rules-for-entering-england

No, France doesn't have any type of “pre-arrival” countdown of a number of days before/after which you are “cleansed/dirty” by passing through any given country. Italy counts back , I know, and several other countries. but France does not.

We just arrived in France two days ago -- no test required, just vaccination card and passport; the attestation form is 'required' but no one looked at ours. Friends who arrived a week ago were asked for their attestation forms, so you probably do need them even if they are not requested.

It is super important to have the pass sanitaire as we get asked for it everywhere. Even to approach the Arc de Triomphe today where the Christos wrap is still up we had to have the pass to enter. People report that CDC cards are accepted, but it sure it nice to have the pass and not have to worry about it. We have been asked for it sitting outside at cafes, at restaurants, at museums and today at the Arc.

Thank you, all!!!
Was wondering about the 'attestation form'. Is it something that we download from a website and carry with us always? Or does the airlines provide it?

From the many posts on this forum from people in France now, a CDC card works just as well as the Passe Sanitaire.

We downloaded the attestation form from our airline site and filled it out. I think you can get one at check in if you don't have one but am not sure, since we had ours. We don't have the one required to enter the US on return so we assume it will be available at the airport.

You can also download the declaration from the link I provided in my answer above by clicking on the word here.

Thanks everyone for all your help!

And no you don’t have to carry the attestation form with you all the time. It is for entry into France.

Thank goodness, the days where we had to carry an attestation form with us, dated, with time, and signed, are in the past (knock on wood).

@Kim- thanks! With so many i's to dot and t's to cross now, I am getting paranoid. lol! I miss those days of relatively stress-free travel.

Getting on any US flight seems to require a test, no matter where you are going. The French didn't care as long as we had a vax card, but transiting Iceland, they required a test.