Case-control study of allergic reactions to Japanese encephalitis vaccine

Japanese encephalitis (JE) vaccine is widely used in Asia For childhood imm unizations, but the vaccine is also used for travellers to Asia from other parts of the world. In Denmark. more than 400,000 doses have been distribut ed from Statens Serum Institut since 1982. In 1989, the first allergic muco cutaneous reactions after JE vaccination were registered in Denmark and. al though the number of reactions have decreased since 1992, reactions are sti ll observed. No explanation of these reactions have been found. The present case-control study. including 49 travellers with allergic reactions and 14 8 travellers without similar reactions after JE vaccination was performed i n order to clarify any possible risk factors. About one third of the advers e reactions to the vaccine could be attributed to an allergic predispositio n in the vaccinees. The main risk factors were young age, female fender and previous allergic skin reactions or hayfever. The study also indicated tha t cases more often reacted to nickel and mole often had severe edema after mosquito or other insect bites. Hormone intake was more often spontaneously reported by females in the case group. Accordingly, information on any history of allergy in young adults should b e given before JE vaccination, the vaccination should be carried out more t han a week before departure and antihistamine treatment should be available if a reaction occurs. (C) 2000 Published by Elsevier Science Ltd. All righ ts reserved.