You know you can get a yellow fever vaccination at the airport. I had a Yellow fever card from the Army, didn't bring it on my first trip to Kenya went to an office right in the airport paid 10 bucks got the shot and was on my way. Trust me over than the distance it's not hard to travel to Africa.
You're american though right? Your passport is different breh
To even get a visa when I went to nigeria i had to include my yellow fever card in the application