STUDY GROUP ON EECOMMEHDED REQUIREMENTS FOR BIOLOGICAL SUBSTANCES Geneva^ 1-6 September IQ-̂ S STUDY OF SERUM ANTIBODY PRODUCED FOLLOWING YELLOW FEVER VACCINATION

In order to reduce as much as possible the a l l e r g i c reactions after vaccination v i t h 17 D vaccine^ we have since 1953 carried out i n the yellow fever vaccination centre of the Paris Pasteur Institute, a test to ascertain s e n s i t i v i t y to the vaccine In a l l a l l e r g i c persons, i n accordance v i t h the method advocated by our late regretted colleague,' Kouwenaar,'^ of .imsterdam. When there i s an intense l o c a l reaction after intradermal injection of 0.1 ml of vaccine, we prefer not to inject the complementary dose of 0,k ml by the subcuteineous route; instead, we usually advise subsequent 2 completion of the vaccination with the Dakar vaccine. The l a t t e r ie prepared from mouse brain euid Is administered by the s c a r i f i c a t i o n method. I t Is much less l i k e l y to pjrovoke the a l l e r g i c reactions produced by the I7 D vaccine owing to i t s compositlor and route of introduction. Moreover., although intradermal injection of I7 D vaccine produces a s l i g h t l y lower immunity (on the basis of the quantity of cir c u l a t i n g a n t i body) than does subcutaneous injection of this same vaccine, It should make It possible to avoid any subsequent v i r a l reaction vhich might be caused by the Dakar vaccine If the l a t t e r were used for primary vaccination. I t vas therefore important for us to determine, on the one hand, the degree of ianunizatlon confeired by Intradermal injection of 17 D vaccine and, on the other, the effect of revaccination v i t h the Dakar vaccine, and to compare the results with "those obtained by the usual methods of vaccination. To this end, hO non-allergic airmen volunteered f o r an experiment carried '̂̂ ut at the Dakar Pasteur I n s t i t u t e , On 27 August 195̂ they were given, intradermally, 0.1 m; of 17 D vaccine from batch 56-5, prepared by the Paris Pasteur Institute. On 17 September I956, a f t e r a f i r s t blood sample had been taken, they were revaccinated ORGANISATION MONDIALE DE LA SANTÉ