Safety and immunogenicity of a primary yellow fever vaccination under low-dose methotrexate therapy-a prospective multi-centre pilot study

Background: More people on immunosuppression live in or wish to travel to yellow fever virus (YFV)-endemic areas. Data on the safety and immunogenicity of yellow fever vaccination (YFVV) during immunosuppression are scarce. The aim of this study was to compare the safety and immunogenicity of a primary YFVV between travellers on methotrexate and controls.Methods: We conducted a prospective multi-centre controlled observational study from 2015 to 2017 in six Swiss travel clinics. 15 adults (nine with rheumatic diseases, five with dermatologic conditions and one with a gastroenterological disease) on low-dose methotrexate ( 0.39). No serious reactions occurred. On Day 10, a minority of vaccinees was seroprotected (patients: n= 2, controls: n= 6). On Day 28, all vaccinees were seroprotected.Conclusions: First-time YFVV was safe and immunogenic in travellers on low-dose methotrexate. Larger studies are needed to confirm these promising results.