For example, we had flights booked from San Francisco Airport to Mykonos, Greece. Greece’s requirement at the time stated “vaccine 14+ days before arrival or PCR test within 72 hours of arrival”.
We took the vaccine 16 days before arrival so that’s all well and good, right? Wrong. We had a few options for layovers: Paris and Frankfurt. Frankfurt, at the time, stated all travelers, regardless of whether or not they clear customs and are simply transiting through the airport, are required to have a negative PCR test within 72 hours.
This means that even though you meet the requirements for Greece with the vaccine, you still need to have a negative PCR to get on the plane from SFO to Frankfurt. However, France’s stated requirements at the time said that passengers on a single itinerary were exempt from the negative PCR requirement if it was not required by the final destination.
Therefore, the vaccine holds as your access to that flight. See the difference? We, of course, went with the flight through Paris as getting a PCR test with a guaranteed turnaround is expensive and often, not guaranteed. It is absolutely critical that you check the requirements for both destination AND transit flight.
There are two ways to do this: check the government sites for your layover and destination countries AND check the airport’s website for the layover and destination countries.