I have a 2 month pregnant lady going to stay with her husband in Nairobi, Kenya, and planning for delivery there, should she be vaccinated against Yellow Fever Vaccination or be given a waiver?
Here is how I proceeded
First question in my mind - Is it safe to use this vaccine in Pregnancy, especially in the first trimester?
Yellow fever vaccination is a PRECAUTION ( & not a contraindication) in pregnancy. Since this is a live vaccine and there is a theoretical risk of transmission of the virus to the baby (though this has never been proven to have ever happened!) it is to be used only if the benefits of vaccination outweigh the risks.
As per Drugs.com
"Yellow fever vaccine has been assigned to pregnancy category C by the FDA. Animal studies have not been reported. There are no large-scale controlled safety studies; however, congenital abnormalities have not been reported. The seroconversion rate to vaccines is significantly lower in pregnant women. Serologic testing should be considered to document an immune response. There is a concern that transplacental passage of the virus may occur. The theoretical risks of immunization may be outweighed by the risk of infection and complications to the mother and fetus if the mother is travelling to an area where there is a high risk of acquiring yellow fever infection. Nonimmune women should generally postpone vaccination and travel to endemic/epidemic areas during pregnancy. If travel and/or exposure is unavoidable, vaccination is preferable after the first trimester. Infants of vaccinees should be monitored for congenital infection and other possible adverse effects. Yellow fever vaccine should be given to a pregnant woman only if clearly needed. The U.S. Centers for Disease Control and Prevention (CDC) recommend postponing travel and yellow fever vaccination until 9 months after delivery. If a pregnant woman is traveling to or transiting through areas where a vaccination certificate is required but the disease is not currently a threat, the CDC advise carrying a physician's waiver along with documentation of the waiver on the immunization record."
There are contradictory references regarding using this vaccine in the first trimester, this French reference states that if you have to give the vaccine, the best chances of an immune response are in the first trimester.
The second question in my mind is - Is it effective to give the vaccine in pregnancy?
As seen above, the immune response is sub optimal, and should ideally be checked later. However, these tests are NOT available easily, and would probably be very expensive as well.
Finally, the third and probably the most important question in my mind - is the lady at a high risk for getting Yellow fever disease where she is traveling?
As per this source onTripavisor
"In April 2011, the World Health Authority and therefore the UK National Travel Health Network and Centre, NaTHNaC, changed their advice to travellers, it now says -"There is a low potential for exposure to yellow fever in the North Eastern province, the states of Kilifi, Kwale, Lamu, Malindi, and Tanariver in Coastal province, and the cities of Nairobi and Mombasa."Vaccination is now not normally recommended if you are only visiting these areas.The remaining areas of Kenya are in the red area on the WHO map, which WHO calls the 'endemic' area. They think the disease may be there all the time or may come and go but they also admit ❝the level of transmission may be low and escape detection when only human case surveillance is employed❞. Basically they suspect it is there because they know it is in the countries bordering that area but can't prove it either way, so they err on the side of caution.In May 2013 the Kenyan Government launched an exercise in association with the WHO and others to gather info to support a case to have Kenya removed from the high-risk list of countries and reclassified as a low-risk or no-risk country."
In conclusion : There is a negligible risk of getting Yellow Fever if the lady stays in Nairobi,Kenya till delivery. The risk of Yellow fever vaccine in pregnancy at first trimester is theoretical, but exists. In this situation, looking the benefit versus risk, I would likely issue a medical waiver to this lady and advise her to take the vaccination as per CDC recommendations, 9 months after the delivery of the baby. In the meantime, avoiding insect bites, and avoiding travel to areas with a high risk of Yellow Fever disease would be advised.