In the past, I have made the claim that vaccinations, including vaccination with live attenuated viruses such as yellow fever, are relatively safe post-IRTs (immune reconstitution therapies) such as alemtuzumab, cladribine and HSCT.

I even have two Alemtuzumabers on my books who have both had yellow fever vaccines before travelling to Ecuador and the Galapagos Islands. who I frequently mention in talks who had no problems with the vaccine. I will have to retract that advice. HCPs have just been sent the following warning from the MHRA (Medicines and Healthcare products Regulatory Agency).

Yellow fever vaccine (Stamaril) and fatal adverse reactions: extreme caution needed in people who may be immunosuppressed and those 60 years and older

“We have recently received 2 reports of fatal adverse reactions to the yellow fever vaccine (Stamaril). Due to an increased risk of life-threatening reactions, the vaccine must not be given to anyone with a medical history of thymus dysfunction or who is immunosuppressed. In addition, extreme caution must be used and a careful risk assessment conducted before vaccination of people aged 60 years and older due to a substantially increased risk of such adverse reactions in this age group.”

This is particularly relevant to Alemtuzumabers in that there is recent data that has been presented that it damages the thymus. If you are HCP who works with MSers please read the advice on the MHRA’s website.