Yellow Fever Vaccination and Increased Relapse Rate in Travelers With MS

Farez and Correale. Arch Neurol. 2011 Jun 13. [Epub ahead of print]

A small study that investigated the effect of yellow fever immunization on the subsequent risk of MS relapse in 7 PwMS. Result: The annual exacerbation rate during risk periods following immunization was 8.57, while the relapse rate outside the risk period was only 0.67 (rate ratio = 12.778; P < .001). Three and nine months after immunization, the PwMS showed a significant increase in MRI activity compared with 12 months prior to vaccination. Conclusions: For patients with MS traveling to endemic yellow fever areas, vaccination should be recommended on the basis of carefully weighing the risk of exacerbation against the likelihood of exposure to the yellow fever virus.

"This is a small study but confirms my predictions of live vaccinations to PwMS. It is well established that infections are a potent trigger of MS relapses. It is therefore not surprising that a live vaccine does the same. The good news is that the development of  an inactivated yellow fever vaccine is well advanced. Another issue for PwMS to consider is the risk of exotic infections whilst taking immunosuppressive agents."