Carol I understand what you are saying about Medicare covering medical emergencies outside the US, it is not clear at all - thanks for stressing that.
Because we spend so much time outside the US I’ve talked to reps several times (out of curiosity because of the lack of documentation) and am told each time, verbally, that we are covered (for medical emergencies) where we travel by our Advantage plan. I don’t know if that plan type is the difference or not? Perhaps someone can respond to that. But if it does indeed cover you for medical emergencies (non-COVID-19), it is secondary coverage and the limit of coverage is unclear. So I am just sharing what I have been told, and it’s clear that I do not rely on it since we buy third-party trip insurance...

Regarding coverage SPECIFICALLY FOR sickness from COVID-19, if you read my earlier reply you can see I stress the need to have that in writing. Normally pandemics are NOT covered emergencies. So if COVID-19 coverage is included you will see a specific section devoted to coverage from COVID-19 sickness. These coverages are in effect from the day you start the policy so if you are infected prior to the trip start date you are covered...