If you are entering The Gambia from another country with a risk of Yellow Fever transmission you will need a YF certificate. So if you're arriving from a non-YF country they won't jab you at the airport.
But once you've been in a YF prone country, you'll need to be vaccinated before being allowed to enter another YF prone country (if you are not, they'll keep you in quarantine for 6 days before letting you in!)
It's recommended you be vaccinated against YF for The Gambia anyway, because of the risk of transmission.
Avoid a while lot of hassle and get the jab. You must have it at least 10 days before arriving in a YF prone destination, but it lasts for 10 years. almost 10 years ago
According to the information that I have found it is highly recommended but not required unless you are coming from another area that is known to have Yellow Fever like another Sub Saharan African Country. I would go ahead and get it though, who knows when you might want to travel to a country that does require it. Plus it is not that expensive so get the vax. almost 10 years agoAnswered by Leif Ryman via WorldNomads.com