Hello, friends,
After reading of the hurried decision you all face around yellow fever vaccines, I spoke with my husband, who is a board-certified MD specializing in infectious diseases and who has worked in the University of Washington travel medicine clinic the past 10 years.
He gave me some statistics that may help you to make a decision.
Total risk for the two most serious complications of the vaccine is:
1/100,000 for those under 60 years of age
3.5/100,000 for those 60-70
6/100,000 for those over 70
The risk of getting yellow fever is about 50/100,000 if you are in an endemic area ( Senegal looks like the only one you'll visit) for two weeks at peak season, which in Senegal is July-December. The risk is probably lower if you stay in urban areas. So, you will be traveling outside the peak season and for just a day or two. Using lots of mosquito spray with as high a percentage of DEET as you can tolerate will be very protective, as will keeping your skin covered as much as is possible. My husband believes the actual risk of contracting YF will be < 7/100,000 if you use the above mosquito precautions, since you going at a non-peak time.
My husband recommends malaria prophylaxis for those traveling in South Africa, Namibia, and Senegal.
I hope this reaches you all in time to make an informed decision, and we wish you a wonderful adventure as you continue the world cruise!