Originally Posted by
MightyTravels
Yes it's generally a requirement. Good catch.
However it is selectively enforced and some airports have a doctor that can give you a short on arrival.
Ethiopian Airlines does not care and won't check.
However a Yellow Fever shot is a great investment when you go to Africa and is under $100 in the US and under $20 in South East Asia. Worth it.
I updated my post as it seems that South Africa has loosened their requirements for travelers with short transits (<12 hours) in airports.